textproduct: San Juan

KEY MESSAGES

Issued at 1227 PM AST Mon Aug 3 2026

* Dangerous heat will continue across Puerto Rico and the U.S. Virgin Islands throughout much of the week. Additional Heat Products will likely be required in the next few days, especially between Wednesday and Thursday.

* A drier air mass with Saharan dust will continue to overspread the region tonight, resulting in hazy skies, reduced air quality, and above-normal temperatures with a generally lower rainfall coverage.

* A trade wind perturbation will increase moisture, potentially leading to more frequent showers across the US Virgin Islands and Puerto Rico tomorrow.

* Increasing easterly winds will deteriorate marine and beach conditions from Thursday onward, resulting in choppy seas and a moderate risk of life-threatening rip currents along north- and east-facing beaches in the USVI and PR.

Short Term(This evening through Wednesday)

Issued at 1227 PM AST Mon Aug 3 2026

This morning, warmer-than-normal temperatures persisted across Puerto Rico and the U.S. Virgin Islands, with most urban and coastal areas recording highs in the low 90s or upper 80s. Heat indices were mainly between 100 and 110 across most urban and coastal locations, where a Heat Advisory is in effect through 5 PM AST. Winds remained mainly from the east between 10 and 20 mph, with higher gusts and sea-breeze variations. Skies remained hazy due to a dry air mass with suspended Saharan dust particles, which overspread the region.

Rain activity is expected to be limited this afternoon, mainly due to local effects, sea breeze variations, and diurnal heating across the interior and western PR, with some showers moving inland across the USVI and the windward sections of PR. But in general, the weather pattern will be dominated by a dry air mass with suspended dust particles from the Sahara, little or no rain, and above-normal temperatures.

Expect a warmer-than-normal night due to suspended dust particles from the Sahara Desert, which will reduce the radiational cooling that normally occurs overnight. Late tonight into early Tuesday morning, a trade wind perturbation will increase the potential for passing showers across the US Virgin Islands and PR's windward locations. Winds will also turn more to the east-northeast. Although we are not anticipating widespread flooding, periods of moderate to locally heavy rain could result in water ponding across roadways and poorly drained areas. The available moisture will then promote afternoon convection and possibly one or two isolated thunderstorms across the interior and western sections of PR.

On Wednesday, the winds will be from the east-southeast, pooling additional moisture over the region. At the same time, model guidance is suggesting above normal temperatures at 925 mb, with values near two standard deviations with respect to August climatology, which, combined with the available moisture, could result in an elevated to significant chance of observing extreme heat during the afternoon hours, which could require Heat Advisories or Extreme Heat Warnings. In terms of precipitation, the typical advective rain pattern across the windward locations, followed by afternoon convection, will persist.

Long Term(Thursday through Monday)

Issued at 329 AM AST Mon Aug 3 2026

Variable weather conditions remain in the long-term outlook under the influence of a broad high-pressure system extending over the western to central Atlantic. This system will promote moderate east- to-southeast winds through most of the period. As noted in previous discussions, this weather pattern will bring patches of low-level moisture into the region from time to time, along with drier air in between, maintaining precipitable water content (PWAT) at below- normal to normal levels for the month of August (1.40 to 2.00 inches). No significant rainfall or thunderstorm activity is expected during this period. While passing showers will move across the U.S. Virgin Islands and eastern Puerto Rico in the morning, they will not lead to notable accumulations. Afternoon convective activity across the interior toward central and western/northwestern Puerto Rico could result in localized showers and isolated thunderstorms at times, driven by available moisture, diurnal heating, and local orographic effects. Therefore, the flooding risk will be none to limited.

Overall, the forecast remains on track for excessive heat persisting through the end of the week. Above-normal temperatures at the 925 mb level will bring daytime highs into the upper 80s and low 90s across coastal and urban areas each day. Combined with the east- southeasterly winds and available moisture, these temperatures could produce high heat indices throughout the period. Please stay hydrated, limit heat exposure, seek air-conditioned areas, and continue to monitor weather conditions as the week progresses.

AVIATION

(18Z TAFS) Issued at 1227 PM AST Mon Aug 3 2026

Mainly VFR conditions will prevail. HZ will continue, although a gradual decrease is expected aft 04/14z. SHRA can develop ovr interior to W PR through 23z. Winds becoming light and variable aft 03/23z, shifting more ENE and incrsng once again to 14-17kts with higher gusts aft 04/12Z. Passing SHRA may increase ovr TJSJ/TIST/TISX late tonight, with SHRA/VCTS devlp aft 04/15Z impacting TJPS/TJBQ. Reduce VIS/CIGs possible ovr TJPS.

MARINE

Issued at 1227 PM AST Mon Aug 3 2026

East-southeast winds will continue tonight, shifting to the east- northeast on Tuesday as a trade wind perturbation moves across the local waters. Moderate to locally fresh easterly winds creating choppy seas are expected from midweek onward as high pressure strengthens over the central Atlantic. Another tropical wave is forecast to approach and move across the local waters during the upcoming weekend.

BEACH FORECAST

Issued at 1227 PM AST Mon Aug 3 2026

A moderate risk of life-threatening rip currents will continue tonight for east- and north-facing beaches in PR and the USVI. The risk will decrease to low on Tuesday and Wednesday as winds weaken. However, even in low-risk areas, dangerous rip currents can still occur, especially near groins, jetties, reefs, and piers. Beachgoers should exercise caution and swim near a lifeguard whenever possible.

The rip current risk is expected to increase back to moderate on Thursday and persist through the weekend for beaches along the north and east coasts of Puerto Rico, including Vieques and Culebra, as well as the U.S. Virgin Islands, as easterly winds strengthen. Under a moderate risk, life-threatening rip currents are possible. Beachgoers should use extra caution before entering the water and heed the advice of local beach officials.

Isolated thunderstorms may develop across western Puerto Rico on Tuesday afternoon, producing frequent lightning, gusty winds, and locally hazardous beach conditions.

In addition, an elevated to locally significant heat risk is expected through midweek. Those planning outdoor beach activities should stay well hydrated, take frequent breaks in the shade, and avoid prolonged exposure during the hottest part of the day.

FIRE WEATHER

Issued at 1227 PM AST Mon Aug 3 2026

A Fire Danger Statement remains in effect through 5 PM AST this afternoon for the southern coastal plains of Puerto Rico. Critically dry fuels persist across these areas, with KBDI values remaining above 683 along the southern half of PR and the USVI. This afternoon, minimum relative humidity values will continue to fall into critical thresholds while sustained easterly winds of 14 to 20 mph, with gusts between 20 and 30 mph, support an elevated risk for rapid fire spread. Although isolated showers are possible elsewhere, little to no wetting rainfall is expected across the driest fuels of southern Puerto Rico and the U.S. Virgin Islands.

Limited to elevated fire weather conditions are expected to persist through the next several days as critically dry fuels remain in place and breezy trade winds continue. Residents and visitors should avoid outdoor burning and exercise caution with any activity that could produce sparks or open flames, especially across areas with critically dry vegetation.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007- 008-010>013.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

AM...None.