{"id":5699,"date":"2026-09-23T20:14:29","date_gmt":"2026-09-23T20:14:29","guid":{"rendered":"https:\/\/ialert.com\/blog\/?p=5699"},"modified":"2026-09-23T20:14:29","modified_gmt":"2026-09-23T20:14:29","slug":"big-island-hurricane-threat-sep-23","status":"publish","type":"post","link":"https:\/\/ialert.com\/blog\/news-events\/big-island-hurricane-threat-sep-23\/","title":{"rendered":"Big Island Hurricane Threat: Tropical Depression Fifteen-E Forecast to Reach Major Hurricane Strength by Saturday"},"content":{"rendered":"<br \/>\n<figure style=\"margin:0 0 18px 0;\">\n  <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/ialert.com\/blog\/wp-content\/uploads\/2026\/09\/ialert-big-island-hurricane-threat-forecast-cone-september-23-2026.jpg\" alt=\"Big Island \n  hurricane threat: National Hurricane Center forecast cone for Tropical Depression Fifteen-E, showing a Category 3 hurricane southeast of the Big Island \n  of Hawaii early Saturday, September 26, 2026\" width=\"1578\" height=\"830\" style=\"max-width:100%;height:auto;\"><figcaption style=\"font-size:14px;color:#555;margin-top:6px;\">Forecast cone for the Big Island hurricane threat: Tropical Depression Fifteen-E is<br \/>\n  forecast to pass about 80 miles southeast of South Point as a Category 3 hurricane early Saturday. Source: NOAA National Hurricane Center, Advisory 12,<br \/>\n  5 AM HST September 23, 2026.<\/figcaption><\/figure>\n<p>The Big Island hurricane threat is rising quickly as Tropical Depression Fifteen-E, centered about 320 miles south-southeast of South Point, Hawaii,<br \/>\n  at 5 AM HST on Wednesday, September 23, 2026, is forecast to become a tropical storm later today, a hurricane on Thursday, and possibly a major<br \/>\n  hurricane by the weekend. Forecasters expect rainfall totals of 15 to 20 inches across the Big Island, with maximum amounts near 35 inches, which may<br \/>\n  produce catastrophic, life-threatening flooding and mudslides in areas of steep terrain.<\/p>\n<p><strong>Big Island hurricane threat, key points:<\/strong><\/p>\n<ul>\n<li>Fifteen-E: 35 mph, about 320 miles south-southeast of South Point, Hawaii.<\/li>\n<li>Forecast: tropical storm today, hurricane Thursday, 115 mph by Saturday.<\/li>\n<li>Closest forecast point: about 80 miles southeast of South Point, 2 AM HST Saturday.<\/li>\n<li>Rain: 15 to 20 inches on the Big Island, 5 to 10 inches on Maui.<\/li>\n<li>A Hurricane or Tropical Storm Watch will likely be required for part of the state later today.<\/li>\n<li>Life-threatening surf adds to the Big Island hurricane threat starting Friday.<\/li>\n<\/ul>\n<div style=\"background: #000000; padding: 20px 24px; margin: 20px 0; border-radius: 4px;\">\n<p style=\"color: #ffffff; font-size: 16px; font-weight: bold; margin: 0 0 6px 0;\">Get Severe Weather Alerts for Your Location<\/p>\n<p style=\"color: rgba(255,255,255,0.9); margin: 0 0 14px 0;\">When any NWS watch, warning, or advisory is issued for your area, iAlert sends you an immediate notification by email, text message, or phone call, 24 hours a day, 7 days a week.<\/p>\n<p><a href=\"https:\/\/ialert.com\/services\/severe-weather-alerts.php\" style=\"background: #C41226; color: #ffffff; padding: 10px 22px; text-decoration: none; border-radius: 3px; font-weight: bold; display: inline-block;\">Sign Up for Severe Weather Alerts &rarr;<\/a>\n<\/div>\n<h2>Where the Big Island hurricane threat stands now<\/h2>\n<p>At 5 AM HST (1500 UTC, 8:00 am PDT, 11:00 am EDT) Wednesday, the center of Tropical Depression Fifteen-E was near latitude 14.5 North, longitude<br \/>\n  154.4 West, about 320 miles south-southeast of South Point, Hawaii, and about 525 miles south-southeast of Honolulu. Maximum sustained winds were near<br \/>\n  35 mph with higher gusts, and the minimum central pressure was estimated at 1004 mb (29.65 inches).<\/p>\n<p>The depression was moving west-northwest near 6 mph. A tropical depression has sustained winds of 38 mph or less; a tropical storm runs 39 to 73 mph,<br \/>\n  a hurricane 74 mph or more, and a major hurricane is Category 3 or higher at 111 mph or more.<\/p>\n<p>No watches or warnings were in effect at advisory time. The National Hurricane Center, which is issuing the Central Pacific Hurricane Center<br \/>\n  advisories on this system, states that a Hurricane or Tropical Storm Watch will likely be required for a portion of the state later today, and that<br \/>\n  interests across the Hawaiian Islands should closely monitor the system. The next complete advisory is due at 11 AM HST (5:00 pm EDT). If you are<br \/>\n  unclear on the difference between a watch and a warning, iAlert covers the terms in <a \n  href=\"https:\/\/ialert.com\/blog\/weather-articles\/know-the-hurricane-hazard-terms\/\">know the hurricane hazard terms<\/a>.<\/p>\n<p>For now the Big Island hurricane threat is a forecast rather than an observation. The system is still a depression, the closest approach is roughly<br \/>\n  three days out, and that is the window in which preparation is advised<\/p>\n<h2>Forecast track and intensity behind the Big Island hurricane threat<\/h2>\n<p>Forecasters expect the west-northwest motion to continue for the next day or so, followed by a sharp turn to the north and north-northeast on<br \/>\n  Thursday that continues through the end of the week. On that track, the system approaches the Big Island of Hawaii on Friday and Saturday.<\/p>\n<p>The official forecast brings Fifteen-E to tropical storm strength by 2 PM HST Wednesday, to a Category 1 hurricane at 75 mph by 2 PM HST Thursday,<br \/>\n  and to a peak of 115 mph at both the 2 AM HST Saturday, September 26, and 2 AM HST Sunday, September 27, forecast points. The closest forecast point to<br \/>\n  South Point, Hawaii, is about 80 miles southeast of it at 2 AM HST Saturday, as a Category 3 hurricane with 115 mph winds; the closest point to Honolulu<br \/>\n  is about 230 miles south-southeast at 2 AM HST Sunday.<\/p>\n<p>Uncertainty is real and quantified: NHC average track errors run about 175 miles on day 4 and 230 miles on day 5, with intensity errors near 23 mph<br \/>\n  each day. The forecast cone shows the probable track of the center, not the size of the storm or the reach of its impacts, so the Big Island hurricane<br \/>\n  threat is not confined to the line on the map.<\/p>\n<p><strong>Advisory 12 forecast track behind the Big Island hurricane threat.<\/strong> Distances are measured from South Point, the southern tip of the<br \/>\n  Big Island.<\/p>\n<p><\/p>\n<div style=\"overflow-x:auto;margin:0 0 20px 0;\">\n<table style=\"width:100%;border-collapse:collapse;font-size:15px;\">\n<thead>\n<tr style=\"background:#f1f4f7;\">\n<th style=\"text-align:left;padding:8px;border:1px solid #d8dde3;\">Forecast time (HST)<\/th>\n<th \n  style=\"text-align:left;padding:8px;border:1px solid #d8dde3;\">Position<\/th>\n<th style=\"text-align:left;padding:8px;border:1px solid #d8dde3;\">Max<br \/>\n  winds<\/th>\n<th style=\"text-align:left;padding:8px;border:1px solid #d8dde3;\">Status<\/th>\n<th style=\"text-align:left;padding:8px;border:1px solid \n  #d8dde3;\">Distance from South Point, Hawaii<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Wed Sep 23, 5 AM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">14.5N 154.4W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">35 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Tropical depression<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">320 mi SSE<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Wed Sep 23, 2 PM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">14.7N 155.2W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">45 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Tropical storm<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">295 mi S<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Thu Sep 24, 2 AM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">15.0N 155.5W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">60 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Tropical storm<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">270 mi S<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Thu Sep 24, 2 PM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">15.7N 155.2W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">75 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Category 1 hurricane<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">225 mi S<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Fri Sep 25, 2 AM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">16.7N 154.8W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">90 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Category 1 hurricane<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">165 mi SSE<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Fri Sep 25, 2 PM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">17.6N 154.5W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">105 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Category 2 hurricane<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">120 mi SE<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Sat Sep 26, 2 AM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">18.2N 154.7W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">115 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Category 3 hurricane<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">80 mi SE<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Sun Sep 27, 2 AM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">18.1N 157.0W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">115 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Category 3 hurricane<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">105 mi WSW<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Mon Sep 28, 2 AM<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">18.7N 160.2W<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">110 mph<\/td>\n<td style=\"padding:8px;border:1px solid #d8dde3;\">Category 2 hurricane<\/td>\n<td \n  style=\"padding:8px;border:1px solid #d8dde3;\">295 mi W<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<h2>Meteorologist&#8217;s take on the Big Island hurricane threat<\/h2>\n<p>Satellite imagery shows the depression becoming better organized, with banding features more defined on the western and northern sides and expanding<br \/>\n  outflow. The catch is structural: the low-level circulation sits on the southeastern edge of the deep convection and is not well aligned with the deep<br \/>\n  convective mass, and satellite intensity estimates spread widely, from about 25 to 40 knots (30 to 45 mph). That misalignment is why forecasters held<br \/>\n  the initial intensity at 30 knots, a value also supported by a recent OSCAT scatterometer pass, and expect slow strengthening at first.<\/p>\n<p>Once an inner core develops, the environment looks favorable: low vertical wind shear, high mid-level moisture, and sea surface temperatures of 28 to<br \/>\n  29 degrees Celsius (82 to 84 degrees Fahrenheit). Rapid intensification probabilities are increasing, and the two best-performing model aids, Google<br \/>\n  DeepMind and HCCA, both show a major hurricane in a few days, which is why the NHC intensity forecast was raised from the previous advisory.<\/p>\n<p>The track reasoning is where the Big Island hurricane threat gets complicated. A ridge northeast of Hawaii is forecast to weaken and slide eastward<br \/>\n  as a mid-latitude trough drops over the northwestern Hawaiian Islands, an evolution likely to cause the cyclone to slow later today or tonight and then<br \/>\n  turn northward or north-northeastward by Thursday with some increase in forward speed. The trough is then forecast to move westward this weekend as the<br \/>\n  ridge rebuilds north of Hawaii, which should force a sharp westward turn while the cyclone is close to the Big Island.<\/p>\n<p>Exactly when that turn happens is unknowable at this range, and there is a large north-south spread in the guidance. The current NHC forecast sits on<br \/>\n  the northern side of the track envelope, meaning small timing shifts translate into large differences in how close the center comes to land. The scale<br \/>\n  of the Big Island hurricane threat hinges on the timing of that turn at least as much as on peak intensity.<\/p>\n<h2>Rain, flooding, and surf hazards in the Big Island hurricane threat<\/h2>\n<p>Rainfall is the headline hazard, and it is the first piece of the Big Island hurricane threat to arrive. The Big Island is forecast to see 15 to 20<br \/>\n  inches with maximum amounts of 35 inches, and that rainfall may produce catastrophic, life-threatening flooding and mudslides, especially in areas of<br \/>\n  steep terrain. Maui is forecast to see 5 to 10 inches with maximum amounts of 20 inches, with life-threatening flooding and mudslides possible, again<br \/>\n  most likely over high terrain.<\/p>\n<p>Across the rest of the Hawaiian Islands, totals of 1 to 3 inches with maximum amounts of 6 inches are expected, with isolated flooding possible, so<br \/>\n  the rainfall side of the Big Island hurricane threat falls off sharply west of Maui. Heavy rain becomes more likely on Thursday and Friday and is likely<br \/>\n  to continue across the Big Island and Maui through the weekend.<\/p>\n<p>Swells are expected to reach the east and south-facing shores of the Big Island on Friday, spreading westward and building through the weekend, and<br \/>\n  those swells are likely to cause life-threatening surf and rip current conditions. There is an increasing risk of wind impacts in the Hawaiian Islands<br \/>\n  regardless of the exact track. Mariners should note that NHC has requested 3-hourly ship reports within 300 miles of the center.<\/p>\n<h2>How to stay safe in the Big Island hurricane threat<\/h2>\n<p>Use the time available today. Forecasters say the time to prepare for significant heavy rain and flooding impacts on the Big Island is now, before<br \/>\n  conditions deteriorate on Thursday and Friday. Finish supply runs, secure loose outdoor items against wind, and confirm that your household preparedness<br \/>\n  plan is in place.<\/p>\n<p>Know your flood and landslide exposure. With 15 to 20 inches of rain forecast for the Big Island and up to 20 inches possible on Maui, steep terrain,<br \/>\n  stream crossings, and low-lying roads are the danger zones. Never drive into water covering a road, and move to higher ground if water begins rising<br \/>\n  near your home; iAlert&#8217;s guide to <a href=\"https:\/\/ialert.com\/blog\/weather-articles\/flood-safety-during-a-flood\/\">flood safety during a flood<\/a> covers<br \/>\n  the rest.<\/p>\n<p>  the rest.<\/p>\n<p>Stay out of the ocean once swells arrive on Friday, because life-threatening surf and rip currents are expected along east and south-facing shores.<br \/>\n  Track watch and warning updates on the <a href=\"https:\/\/ialert.com\/hurricanes.php\">iAlert hurricane tracker<\/a> and keep <a \n  href=\"https:\/\/ialert.com\/analysis.php#alerts\">active weather alerts<\/a> open on your phone, since a watch may be issued for part of the state later<br \/>\n  today. Residents and visitors should treat the Big Island hurricane threat as a plan-now situation rather than a wait-and-see one.<\/p>\n<h2>Big Island hurricane threat FAQ<\/h2>\n<h3>Does Tropical Depression Fifteen-E create a Big Island hurricane threat?<\/h3>\n<p>Yes. Forecasters say there is an increasing risk of wind and wave impacts in the Hawaiian Islands regardless of the exact track, and the system is<br \/>\n  expected to approach the Big Island on Friday and Saturday.<\/p>\n<h3>How strong could the storm get?<\/h3>\n<p>The forecast peaks at 115 mph, a Category 3 major hurricane, at the 2 AM HST Saturday, September 26, and 2 AM HST Sunday, September 27, forecast<br \/>\n  points. NHC intensity errors average about 23 mph per day.<\/p>\n<h3>Where is the storm headed?<\/h3>\n<p>West-northwest near 6 mph for the next day or so, then a sharp turn to the north and north-northeast on Thursday. The closest forecast point is about<br \/>\n  80 miles southeast of South Point at 2 AM HST Saturday.<\/p>\n<h3>Is a hurricane watch in effect for the Big Island?<\/h3>\n<p>Not as of Advisory 12. NHC says a Hurricane or Tropical Storm Watch will likely be required for a portion of the state later today, and that a<br \/>\n  Hurricane Watch may be required for the Big Island. That would be the first official watch tied to this Big Island hurricane threat, and a watch means<br \/>\n  hurricane conditions are possible within 48 hours.<\/p>\n<h3>When do impacts begin on the islands?<\/h3>\n<p>The Big Island hurricane threat starts with rain. Heavy rain becomes more likely on Thursday and Friday and continues through the weekend on the Big<br \/>\n  Island and Maui. Swells reach east and south-facing Big Island shores on Friday, building westward through the weekend.<\/p>\n<p>iAlert will update this post as new advisories arrive. The Big Island hurricane threat is re-evaluated on a six-hour cycle, with complete advisories<br \/>\n  at 5 AM, 11 AM, 5 PM, and 11 PM HST.<\/p>\n<p><strong>Sources:<\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/www.nhc.noaa.gov\/archive\/2026\/ep15\/ep152026.public.012.shtml\" target=\"_blank\" rel=\"noopener\">NHC\/CPHC Tropical Depression Fifteen-E Public Advisory Number<br \/>\n  12<\/a><\/li>\n<li><a href=\"https:\/\/www.nhc.noaa.gov\/archive\/2026\/ep15\/ep152026.discus.012.shtml\" target=\"_blank\" rel=\"noopener\">NHC\/CPHC Tropical Depression Fifteen-E Forecast Discussion Number<br \/>\n  12<\/a><\/li>\n<li><a href=\"https:\/\/www.nhc.noaa.gov\/archive\/2026\/ep15\/ep152026.fstadv.012.shtml\" target=\"_blank\" rel=\"noopener\">NHC\/CPHC Tropical Depression Fifteen-E Forecast\/Advisory Number<br \/>\n  12<\/a><\/li>\n<\/ul>\n<div style=\"background: #000000; padding: 20px 24px; margin: 20px 0; border-radius: 4px;\">\n<p style=\"color: #ffffff; font-size: 16px; font-weight: bold; margin: 0 0 6px 0;\">Get Severe Weather Alerts for Your Location<\/p>\n<p style=\"color: rgba(255,255,255,0.9); margin: 0 0 14px 0;\">When any NWS watch, warning, or advisory is issued for your area, iAlert sends you an<br \/>\n  immediate notification by email, text message, or phone call, 24 hours a day, 7 days a week.<\/p>\n<p>  <a hre\n<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Big Island hurricane threat grows: Fifteen-E, 320 miles south-southeast of South Point, Hawaii, could reach Category 3 by Saturday.<span class=\"more\"> <a href=\"https:\/\/ialert.com\/blog\/news-events\/big-island-hurricane-threat-sep-23\/\">Read More&#8230;<\/a><\/span><\/p>\n","protected":false},"author":6,"featured_media":5703,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","rank_math_focus_keyword":"Big Island hurricane threat","rank_math_title":"Big Island Hurricane Threat: 115 mph Cat 3 Eyed Saturday","rank_math_description":"Big Island hurricane threat grows: Fifteen-E, 320 miles south-southeast of South Point, Hawaii, could reach Category 3 by Saturday."},"categories":[719],"tags":[151],"class_list":["post-5699","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news-events","tag-tropical-storm"],"acf":[],"_links":{"self":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5699","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/comments?post=5699"}],"version-history":[{"count":4,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5699\/revisions"}],"predecessor-version":[{"id":5704,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5699\/revisions\/5704"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/media\/5703"}],"wp:attachment":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/media?parent=5699"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/categories?post=5699"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/tags?post=5699"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}