textproduct: San Juan

KEY MESSAGES

Issued at 229 PM AST Wed Mar 11 2026

* Frequent passing showers are expected to continue, with afternoon showers and isolated thunderstorms possible over western Puerto Rico during the afternoon hours, particularly today and Thursday.

* Slightly drier trend for Friday and especially Saturday, but showers may develop over the western interior of PR during the afternoon hours.

* Lighter winds are expected Thursday through early Saturday, however, winds are forecast to increase around Saturday night into Sunday, leading hazardous marine and beach conditions.

* Across the U.S. Virgin Islands, occasional passing trade wind showers will continue, with a drying trend expected by Friday and Saturday.

Short Term(This evening through Friday)

Issued at 229 PM AST Wed Mar 11 2026

Mostly cloudy skies and scattered showers were observed across the islands today. As of 1 PM, the Doppler radar estimated between half to an inch of rain with the heaviest showers. Wind gusts were between 22 and 32 mph. High temperatures were from the low to mid- 80s in general across the lower elevations. For the rest of this afternoon, cloudiness and shower activity will persist over the western half of PR, while trade wind showers continue to move at times across the USVI and eastern coastal areas of PR.

In terms of moisture content and shower potential, an upper level trough and induced low-level trough will continue to promote an increase in showers through late Thursday/early Friday morning. Isolated thunderstorms are expected to develop late this afternoon, and once again on Thursday as the trough pattern promotes an unstable atmosphere. Urban and small stream flooding is expected with this activity, particularly on Thursday, as winds decrease and promote slow-moving showers over the mountain ranges. Strong gusty winds are also expected with this activity.

Drier air and more stable conditions will gradually filter over the region late in short-term period. However, lingering moisture content and the proximity of the short-wave trough aloft will still cause showers and possible isolated thunderstorms to develop over the western interior of PR during the afternoon hours.

LONG TERM(Saturday through Wednesday)

Issued at 320 AM AST Wed Mar 11 2026

Current model guidance suggests PWAT values around 1.20 to 1.40 inches on Saturday, increasing to around 1.6 inches on Sunday as a patch of more humid air approaches the area. Favorable conditions for shower development will continue as a jet stream aloft continues to promote ventilation to accompany the low level moisture approaching the area. This can promote vertical shower development and possible t-storm formation, particularly during afternoon convection over interior to southwestern PR on Saturday under ENE flow and interior to northwestern PR under ESE flow Saturday onwards, as well as lines of showers from the USVI, Vieques and Culebra to ESE PR. Sunday appears to be the wettest day of the weekend. A broad surface high will move into the western Atlantic and continue building, promoting increased wind speeds. 925 mb wind speeds will be above normal, resulting in breezy to locally windy conditions to start the next week. For the first half of the next workweek, more stable conditions will dominate with warmer 500 mb temperatures. This will serve to limit shower development, however breezy ESE flow will steer showers and patches of moisture towards windward sectors with diurnal heating promoting afternoon convective showers over interior to northwestern PR, as well as lines of showers towards the local islands. 925 mb temperatures will remain at normal values but under a general warming trend with less cloud cover.

AVIATION

(18Z TAFS) Issued at 229 PM AST Wed Mar 11 2026

Mainly VFR conditions expected through most of the fcst period. Locally induced SHRA and possible iso TSTMs over western PR may lead to tempo MVFR conds thru 11/22z. Elsewhere, trade wind SHRA will move at times through Thursday morning, causing brief MVFR cigs, particularly at TIST. The 11/12z TJSJ sounding indicated east winds up to 24 kt blo 3000ft.

MARINE

Issued at 229 PM AST Wed Mar 11 2026

A surface high pressure across the Atlantic will promote mainly gentle to moderate easterly winds tonight. Seas are forecast to remain around 4 to 6 feet across offshore waters and passages, as a result, small craft operators should exercise caution. Improving marine conditions are forecast toward the end of the week, as winds are expected to remain gentle to moderate and seas decrease to between 3 and 5 feet. However, winds are forecast to start increasing again around Saturday night into Sunday, leading to rough and choppy seas and likely prompting Small Craft Advisory conditions from late in the weekend into early next week, with seas building to around 6 to 8 feet.

BEACH FORECAST

Issued at 229 PM AST Wed Mar 11 2026

Life-threatening rip currents are possible tonight along the north, east, and southeast coastlines of Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands as a moderate risk continues. By Thursday, winds are expected to subside, resulting in improved conditions, however, the rip current risk will remain moderate along north and east-facing beaches of Puerto Rico, Culebra, and St. Croix, and decrease to low elsewhere. The same pattern will continue through early Sunday.

The risk is forecast to increase to high around Sunday night into early next week, along with breezy to windy conditions. Residents and visitors are encouraged to monitor the forecast for any updates or adjustments. For additional information and location- specific rip current details, please visit: weather.gov/beach/sju.

FIRE WEATHER

Issued at 229 PM AST Wed Mar 11 2026

The KBDI remains above critical fire weather thresholds in Cabo Rojo (670) and below thresholds in Guanica (520) and Camp Santiago (390). Around 10 AM AST and noon, surface observations showed RH values in the low 50s in Cabo Rojo and other areas in southern areas of Puerto Rico and also in St. Thomas. The rest of the afternoon, passing showers will continue to move across the area from time to time; however, drying soils, lower humidity later in the day and and strong winds will maintain a moderate to elevated fire danger risk today, particularly for southwestern Puerto Rico. Tonight into Saturday, winds are expected to become light to moderate. Additionally, RH values are expected increase due to the arrival of another patch of moisture into the area. At this time an RFD will not be issued, but we encourage partners to continue monitoring conditions in the coming days.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...None.