Glenn James
Hawaii Weather Today
Founder and maintainer for 30 years


The latest update to this website was 326am Sunday HST


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

0.01  Mount Waialeale, Kauai
0.07  Kahuku Trng Area, Oahu
0.01  Keopukaloa, Molokai
0.00  Lanai
0.02  Hana AP, Maui
0.24  Honolii Stream, Big Island


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

18  Barking Sands, Kauai – WNW
24  Waianae Harbor, Oahu – NW
22  Molokai AP, Molokai – NNE
18  Lanai 1,  Lanai – NNE
30  Mamane Pl, Maui – NW
23  South Point, Big Island – ENE


Hawaii’s Mountains – Here’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.

https://weather.gc.ca/data/satellite/goes_gwdisk11_1070_100.jpg

Big Blue…click twice for largest version

 

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 High level clouds moving over the state…from the west

 

https://radar.weather.gov/ridge/standard/HAWAII_loop.gif

https://radar.weather.gov/ridge/standard/PHKI_loop.gif

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Showers locally 

 

https://www.weather.gov/wwamap/png/hfo.png

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




~~~ Hawaii Weather Narrative ~~~

 

Glenn’s Sunday comments:  I’m here in Corte Madera, Marin County, California with my friends Bob and Linllda, continuing on in my working vacation.

 

>>> Highest Temperature Saturday, April 18, 2026 – 97 degrees near Horrel Hill, SC
>>> Lowest Temperature Sunday, April 19, 2026 –  5 degrees at Peter Sinks, Utah

 

Interesting weather Web Blog: Mauka Showers…Mother Nature Reminds Us that April is Still in the Wet Season

 

Hawaii’s Broad Brush Weather Overview…as of Saturday: Moderate trade winds will weaken and veer out of the east-southeast across the western half of the island chain tonight, as low pressure deepens several hundred miles northwest of Kauai. Shower activity should be light and focused mainly over windward areas, as high clouds briefly diminish.

An upper-level trough will will bring increased high clouds and renewed chances for isolated heavy showers and thunderstorms Sunday afternoon and Monday. Light winds favor chances for mainly afternoon showers Tuesday and Wednesday, followed by rebuilding trade winds Thursday and Friday.

Weather Details for the Hawaiian Islands…as of Saturday: An upper-level trough passing overhead has brought extensive high clouds and instability aloft, but moderate easterly trade winds, and a weak low-level ridge have kept shower activity rather minimal, and largely confined to windward and mountain areas. A robust high is centered far north of the state along 40N latitude, but the local pressure gradient has been slightly weakened by a diffuse surface trough sitting several hundred miles northwest of Kauai, resulting in the moderate easterly trade winds.

Afternoon soundings revealed an inversion between 4,000 to 5,000 feet produced by a weak low-level ridge, giving way to instability generated by the upper-level trough. The axis of the upper trough recently triggered a couple of briefly heavy showers over Kauai, and given the shallow stable layer, we still could see a heavy shower flare up as the upper-level trough advances eastward. Easterly trade winds will ease slightly tonight, as developing low pressure several hundred miles north of Kauai continues to erode the surface pressure gradient.

The upper-level trough will flatten as it swings northeast of the islands, and a weak ridge will remain in place. As a result of this tenuous stability, showers will likely remain modest and largely confined to windward slopes. That said, we still cannot rule out a brief and isolated heavy shower anywhere. In addition, expect a short-lived decrease in high clouds. On Sunday and Monday, trade winds will weaken further and will shift out of the east-southeasterly across the western half of the island chain, while another upper-level trough brings instability, mainly Sunday night into Monday morning.

For now, it appears that the deepest moisture and highest chances for widespread rainfall will remain along the surface trough northwest of Kauai, but isolated heavy showers or a thunderstorm remain possible around Kauai. Elsewhere, expect afternoon interior showers and possibly a thunderstorm on Big Island, and another item to monitor will be a chance for localized anchored heavy showers along the Koolau Mountains of Oahu Sunday night. Even though moisture does not appear to be significant on Oahu, the expected veering flow with height has a tendency to produce heavy rain events on the Koolau.

Chances for heavy rainfall look to diminish Tuesday and Wednesday. The upper level trough should move off to the east late Monday, allowing a weak ridge aloft to settle over the state. The GFS and ECMWF models are hinting that the surface trough, that had been lingering northwest of Kauai, will be pushed over the western end of the island chain. This would favor light and variable winds over most areas, with higher rainfall chances over island interiors during the late morning and afternoon hours. Trade winds are expected to rebuild Thursday and Friday.


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 Map / Looping Surface Precipitation…through the next 8-days

 

Marine Environmental Conditions…as of Saturday: A high pressure system far north of the state will slowly drift eastward this weekend. Easterly trade winds continue with Small Craft Advisory conditions in effect for the windier waters and channels near the Big Island and Maui. A series of low pressure systems developing northwest of the islands will weaken the ridge over the state, causing weak southeasterly winds to develop over the western Hawaii region from Sunday into early next week.

A small pulse of medium period swell energy from the northwest should produce a slight bump in north facing surf heights. A small to moderate, medium period northwest swell will move into the region by Monday night and continue through Wednesday. A moderate, medium period northeast swell will arrive by Monday night, peaking from Tuesday to early Wednesday, and then slowly declining through Thursday. A series of overlapping small south swells will move into the region into next week. Surf heights along east facing shores remains on the smaller side due to weaker trade winds.

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Wailea beach path, Wailea Elua, Ulua Beach


World-wide Tropical Cyclone Activity


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


>>> Atlantic Ocean: There are no active tropical cyclones

>>> Caribbean Sea: There are no active tropical cyclones

>>> Gulf of Mexico: There are no active tropical cyclones

Here’s the link to the National Hurricane Center (NHC)

 

>>> Eastern Pacific: There are no active tropical cyclones

Here’s the link to the National Hurricane Center (NHC)

>>> Central Pacific: There are no active tropical cyclones

Here’s the link to the Central Pacific Hurricane Center (CPHC)

 

>>> Northwest Pacific Ocean:

Tropical Cyclone 04W (Sinlaku)…is located approximately 448 NM northwest of Minami Tori Shima

https://www.metoc.navy.mil/jtwc/products/04W_190600sair.jpg

 

>>> Southwest Pacific Ocean: There are no active tropical cyclones

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



Interesting: When Does the Body Clock Begin to Synchronize with Local Time?

Daily rhythms cross placenta from mother to the baby before the fetus can sense light.

Humans and most other organisms have internal biological clocks that track the daily cycle of sunrise and sunset. These clocks help time our sleep, metabolism and other essential body functions over the course of a day, creating daily patterns called circadian rhythms. Research shows that when these rhythms are disrupted — by jet lag, lack of sleep or irregular work schedules — people can suffer long-term negative health effects.

Scientists who study daily rhythms have long wondered about when the mammalian circadian clock starts ticking and synchronizes to local time. In a new study published in the Journal of Biological Rhythms, researchers at Washington University in St. Louis reported that a mother helps to set the biological clock for her babies while they are still in the womb.

“We know that disrupting circadian rhythms during pregnancy can affect how sleep and daily rhythms develop in infants, and these early disruptions are linked to a higher risk of mood disorders such as anxiety and depression later in life,” said Nikhil Lokesh, study author and a research scientist in biology in WashU Arts & Sciences. “Understanding when the fetal clock begins to function helps us identify sensitive developmental windows when circadian disruption may have lasting effects and how those effects might be prevented or corrected.”

Read More: Washington University in St. Louis