Glenn James

Hawaii Weather Today
Creator, Author, and Administrator for 30 years

 

The latest update to this website was at 525pm Sunday evening HST


Here are the latest 24-hour precipitation totals (inches) for each of the island Sunday evening: 

0.18  N Wailua Ditch, Kauai
0.17  Tunnel RG, Oahu
0.04  Puu Alii, Molokai
0.00  Lanai
0.18  West Wailuaiki, Maui
1.33  Kawainui Stream, Big Island


The following numbers represent the strongest wind gusts (mph) Sunday evening:

24  Port Allen, Kauai – E
40  Oahu Forest NWR, Oahu – ENE
33  Makapulapai, Molokai – E 
50  Kealaloloa Rg, Maui – NE 
42  Kawaihae Rd, Big Island – NWE


Hawaii’s MountainsHere’s a link to the live webcam on the summit of our tallest mountain Mauna Kea (~13,800 feet high) on the Big Island of Hawaii. Here’s the webcam for the (~10,023 feet high) Haleakala Crater on Maui. These webcams are available during the daylight hours here in the islands, and at night whenever there’s a big moon shining down. Also, at night you will be able to see the stars, and the sunrise and sunset too…depending upon weather conditions.


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Big Blue…click twice for largest version

 

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Tropical systems remain active in the eastern Pacific…including Tropical Storm Odalys and Tropical Storm Polo 


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Variable low, middle, and high level clouds are present over the island chain

 

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Localized Showers…very few 

 

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Please open this link to see details on any current Watches, Warnings and Advisories noted above




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Hawaii Weather Narrative
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Glenn’s Sunday comments:  I’m at home here in upper Kula, Maui, Hawaii

519am, it’s mostly clear here at my place. The low temperature here in upper Kula was 57 degrees, relative humidity is 80%…with calm winds

1215pm, it’s a mostly sunny day here in Maui County, with just the usual low clouds over the windward sides…and the West Maui Mountains.

445pm, here in Maui County, sunshine has prevailed all day, with just some streaky high cirrus clouds, and of course those few low cumulus clouds here and there….and it’s hazy.

 

>>>Tropical Cyclone Activity – Hawaii:  The unusually warm waters of the tropical eastern and central Pacific continue to promote the formation of tropical systems, as we approach the beginning of our autumn season. Tropical Storm Odalys remains active over in the eastern Pacific, which will strengthen into a hurricane eventually. Fortunately, the NHC forecast keeps it away from our central Pacific. At the same time, Tropical Storm Polo has formed very close to the west coast of mainland Mexico…and may reach major hurricane status by Wednesday or so.

Meanwhile, here in the central Pacific, there’s a chance that Remnants of TC 15E, or it’s associated trough of low pressure, could approach the general area of the Hawaiian Islands later in the upcoming work week. As this area of disturbed weather moves closer, we could see increased moisture, which could potentially lead to heavy rainfall and localized flooding, at least for the Big Island. The best consensus seems to show the core of the low staying south of the Big Island.

It should be noted that the NHC is keeping a close eye on this area of disturbed weather, as some of the forecast models want to redevelop it back into a tropical cyclone. At the time of this writing, there’s a near zero chance of this happening over the next 48 hours, although it becomes a much more favorable 70% chance of forming into a TC within the next 7 days. According to the NHC, environmental conditions are conducive for some development by the middle to latter portion of the upcoming week…as it moves south of, and close to, our island chain.



Hawaii’s Weather Highlights
…as of Sunday evening:
Moderate to locally breezy trade winds will continue through Monday before gradually decreasing by mid-week, and then re-intensifying late in the week. The remnants of TD 15E have a high 70 percent chance of reforming into a tropical system later this week. The track may bring it south of, and close to, the state.

Weather Narrative…as of Sunday evening: The radar remains nearly “empty”, with only isolated light showers seen across the island chain. Showers may also develop over the Kona region on the Big Island, but most folks will remain dry. Trade winds were averaging 10 to 20 mph, with gusts 25 to 35 mph in the usual breezy places. Skies were mostly sunny except for the typical windward/mauka areas.

An upper level low that has been lingering to the north and west of the state, will slowly weaken and pull away to the northeast through late Tuesday. As it does, a new weak trough will move in from the west. Upper level wind flow to our south remains weak, which matters because it may allow the remnants of TD 15E to redevelop this week. NHC has now raised the percentage chance of reformation to 70%, and the GFS and EC models now develop the storm late this week. Both models move it to the south of us.

It is too soon to know what will come of this, but it is well worth keeping an eye on as it may bring (at least) another round of heavy rain to the area. Other than that, we expect trades to continue through the week, growing a little weaker mid-week before strengthening again late in the week. Should a tropical storm develop to our south, it would enhance the pressure gradient, and hence the trade winds.

Again, it is too soon to say whether this will happen, but it seems wise to continue to discuss the possibility. With increased moisture drawn northward by a potential system as depicted in the models, there’s the chance of isolated thunderstorms, mainly over the eastern half of the state, from Tuesday night through mid-day Saturday. There is more uncertainty than usual with the forecast this week, due to this potential tropical system.

Fire Weather: Fire weather risk remains low. Locally breezy trade winds are expected through at least Monday. However, dewpoints in the low 70’s will keep relative humidity in check. Inversion heights are around 6,000 feet.

 

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Here’s a near real-time Wind Profile of the Pacific Ocean – along with a Closer View of the islands / Here’s the latest Weather MapLooping Surface Precipitation…through the next 8-days / Vog Map

 

Marine Conditions…as of Sunday evening: The gradient between weak high pressure north of the islands and pressure falls south of the islands will maintain fresh to locally strong trade winds across the region through at least Monday night. Therefore, the Small Craft Advisory has been extended through Monday night for the typical windy channels and waters of Maui County and the Big Island. After a slight reduction in trade wind speeds heading into mid week, they will restrengthen during the latter half of the week as a trough or potential weak tropical disturbance moves south of the islands. Shower coverage will also increase, along with the potential for isolated thunderstorms, particularly across the eastern waters.

Surf along south facing shores will remain above average over the next couple of days as a long period SSW swell holds relatively steady. This swell will then gradually fade heading into mid week. A slightly smaller, long-period south-southwesterly swell will fill in late this week into next weekend generated by a series of lows near New Zealand. West facing shores will experience a bit of the southerly wrap through most of the week.

Breezy trade winds will maintain moderate surf along east facing shores for the next several days. Surf along north facing shores will remain flat to tiny through Monday, but will see a slight bump Tuesday into Wednesday as a small, medium-period northwest swell fills in from an Aleutian low. Then a small, long-period west-northwest swell expected to be generated by Tropical Storm Dujuan as it curves northeast near Japan and potentially strengthens into a hurricane will build locally Friday into next weekend, increasing surf along north and west facing shores.

 

>>> Highest Temperature Sunday, September 20, 2026 – 108 degrees near Tecopa, CA


>>>
Lowest Temperature Sunday, September 20, 2026 – 22 degrees at Austin, NV

 

Beautiful Pictures Of Hawaii To Brighten Dark Rooms


World-wide Tropical Cyclone Activity

 



>>>
Here’s a link to the latest Pacific Disaster Center’s
Weather Wall




Atlantic Ocean:

Tropical cyclone 6L (Fay) is located about 385 miles southwest of the Azores

FAY NEARLY A HURRICANE BUT FORECAST TO WEAKEN ON MONDAY

According to the NHC advisory number 7

Fay is now moving toward the east-southeast near 5 mph. A turn to the southwest is anticipated on Monday which should continue through the early part of this week. Maximum sustained winds have increased to near 70 mph with higher gusts. Little change is strength is forecast tonight, but Fay should begin to weaken on Monday. The tropical cyclone is forecast to become a post-tropical cyclone by the middle of this week. Tropical-storm-force winds extend outward up to 80 miles from the center. The estimated minimum central pressure is 995 mb (29.39 inches).

cone graphic

 

 Caribbean Sea: There are no active tropical cyclones


Gulf of America:
There are no active tropical cyclones

 

Northeast Pacific:

Tropical cyclone 16E (Odalys) is located about 1350 miles west-southwest of the southern tip of Baja California

 

ODALYS MOVING NORTHWESTWARD …EXPECTED TO BECOME A HURRICANE LATER THIS WEEK

According to the NHC advisory number 4

Odalys is moving toward the northwest near 13 mph, and an abrupt turn toward the east is expected on Tuesday. A gradual turn toward the east-northeast is expected by the middle part of the week followed by a turn toward the northeast by the end of the week. Maximum sustained winds are near 50 mph with higher gusts. Gradual strengthening is expected to resume on Monday, and Odalys is forecast to become a hurricane by mid-week. Tropical-storm-force winds extend outward up to 70 miles from the center. The estimated minimum central pressure is 1002 mb (29.59 inches).

cone graphic

 

Tropical cyclone 17E (Polo) is located about 270 miles south of Manzanillo, Mexico

DEPRESSION BECOMES TROPICAL STORM POLO …FORECAST TO RAPIDLY INTENSIFY INTO A MAJOR HURRICANE

According to the NHC advisory number 2

Polo is now moving toward the east-northeast near 5 mph. A turn toward the east is expected on Tuesday, followed by a decrease in forward speed and a sharp turn toward the north and northwest on Wednesday. Maximum sustained winds have increased to near 40 mph with higher gusts. Rapid intensification is forecast over the next few days, and Polo is expected to become a major hurricane by the middle part of the week. Tropical-storm-force winds extend outward up to 45 miles from the center. The estimated minimum central pressure is 1004 mb (29.65 inches).

https://www.nhc.noaa.gov/storm_graphics/EP17/EP172026_5day_cone.png

 

Central North Pacific: There are no active tropical cyclones

>>> Well East-southeast of the Hawaiian Islands:

(Former TD 15E)

Showers and thunderstorms have increased, but remain disorganized, in association with the remnants of Tropical Depression Fifteen-E, located more than 500 miles to the east-southeast of the Hawaiian Islands. Environmental conditions are forecast to become more conducive for development of this system by the middle to latter portion of this week, and a tropical depression is likely to form by that time to the south or southeast of the Hawaiian Islands as the system moves generally westward at 10 to 15 mph.

* Formation chance through 48 hours…low…near 0 percent
* Formation chance through 7 days…high…70 percent 

 

>>> South of the Gulf of Tehuantepec:

An area of low pressure could form in a few days to the south of the Gulf of Tehuantepec. Thereafter, environmental conditions appear favorable for gradual development while the system moves slowly west-northwestward to northwestward, parallel to the coast of southern and southwestern Mexico.

* Formation chance through 48 hours…low…near 0 percent
* Formation chance through 7 days…low…20 percent

Northwest Pacific Ocean:

Tropical Cyclone 24W (Dujuan)…is located approximately 181 NM south-southwest of Yokosuka, Japan

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Southwest Pacific Ocean: There are no active tropical cyclones

North and South Indian Oceans / Arabian Sea: There are no active tropical cyclones

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Here’s the link to the Joint Typhoon Warning Center (JTWC)



Interesting: 
Why Most Rivers Don’t Respond to Storms the Same Way Twice

The same amount of rain falling on the same landscape at different times can send very different amounts of water into its rivers, according to a new study in Nature Water. The research offers a global picture of how catchments behave—not where rivers are or how much water they carry—but how consistently landscapes turn rainfall into river flow.

“We often imagine a catchment as a pipe—put in a certain amount of rain and get a predictable amount of runoff,” said Dr. Ali Ameli, a hydrologist at the University of British Columbia (UBC) and lead author of the study.

“But most catchments behave more like dynamic systems with a memory. How much of today’s rainfall becomes runoff and reaches the stream depends on both the conditions created by earlier weather and which parts of the landscape supply water to the river during the storm.”

Read More at: University of British Columbia

The forested catchments on Vancouver Island’s west coast are prime examples of simple catchments