textproduct: San Juan

KEY MESSAGES

Updated at 339 AM AST Fri May 8 2026

* Warm to hot weather will continue through the middle of next week, particularly in urban and coastal areas of Puerto Rico and the U.S. Virgin Islands.

* Locally induced afternoon showers are expected to develop each afternoon over portions of western Puerto Rico.

* Across the USVI, mostly fair weather conditions are expected. Passing trade wind showers cannot be ruled out at times.

* A moderate rip current risk will prevail for the north- and east-facing beaches of Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands through the weekend.

Short Term(Today through Sunday)

Issued at 339 AM AST Fri May 8 2026

A mid-level ridge building over the northeastern Caribbean will maintain a predominantly stable and dry weather pattern through the weekend. The GFS indicates that while low-level moisture remains present, a significant dry layer between 700-500mb (with RH values dropping below 30%) and warmer 500mb temperatures up to 4 degrees C will provide strong subsidence and entrainment. This will limit vertical development and the potential for deep convection compared to yesterday. Total precipitable water (PWAT) values are forecast to range between 1.20 and 1.50 inches, which is on the lower end of the climatological normal (near the 25th percentile) for early May, further supporting limited rainfall activity.

Having said that, a surface high pressure north of the region will promote breeze trades around 15-20 knots. This flow will steer occasional shallow moisture patches across the islands, bringing brief, fast-moving showers to windward sections of the USVI and eastern Puerto Rico during the overnight and early morning hours. Diurnal heating and sea breeze convergence will trigger isolated afternoon showers over the interior and western sections of Puerto Rico. Hi-res NBM guidance suggests that daily accumulations will generally remain below half an inch, with only highly localized amounts exceeding that.

The primary concern through Sunday will be the persistent heat risk. With 925mb temperatures remaining above normal (reaching 21-22C) and surface highs nearing 90F in coastal and urban areas, heat indices are expected to exceed 100F.

Long Term(Monday through Friday)

Issued at 339 AM AST Fri May 8 2026

A generally drier-than-normal pattern for shower development will persist through the period as mid-level ridging and subsidence dominate across the region. Moisture will remain below normal for this time of year and mostly confined below 700750 mb, limiting vertical growth and resulting in reduced shower activity. An east to east-southeasterly steering flow will prevail, supporting a consistent daily pattern with brief, quick-moving passing showers affecting windward areas during the overnight and morning hours, followed by isolated afternoon convection over interior to west- northwestern Puerto Rico, driven by local effects and mostly diurnal heating. Isolated thunderstorms cannot be ruled out, but coverage will remain very limited. Minor traces of Saharan dust may be present at times, though concentrations are expected to remain low.

Breezy conditions will increase into the weekend and early next week, particularly across coastal and windward areas, supporting a limited non-thunderstorm wind risk with occasional gusts up to around 25 mph or higher at times. Increasing temperatures combined with warm and humid low-level conditions will promote a limited heat risk each day, mainly affecting sensitive individuals or those with prolonged outdoor exposure and inadequate hydration. In addition, the combination of warm temperatures and increasing winds will maintain the potential for elevated fire danger, particularly across southern and coastal areas where fuels will continue to dry.

AVIATION

(06Z TAFS) Issued at 339 AM AST Fri May 8 2026

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. However, iso -TSRA could develop over the SW quadrant of PR this afternoon, which may cause VCTS at TJPS. Mostly VCSH expected elsewhere. Winds ENE at 15-20 kt

MARINE

Issued at 339 AM AST Fri May 8 2026

A strengthening surface high pressure over the western Atlantic will promote moderate to locally fresh east-to-northeast winds across the regional waters. Therefore, expect choppy marine conditions due to increasing winds. Breezy trade winds will persist into early next week, with occasional winds reaching up to 20 knots. Small craft are urged to exercise caution across portions of the local waters.

BEACH FORECAST

Issued at 339 AM AST Fri May 8 2026

There is a low risk of rip currents across all beaches in PR and the USVI. Nonetheless, life-threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. Beachgoers are encouraged to exercise caution while enjoying the north-and east-facing beaches from Rincon to Fajardo, as well as the northern shores of Culebra and Vieques. Where, locally stronger rip currents are possible.

Increasing winds will promote a moderate risk of rip currents across most of Puerto Rico, and the USVI by the weekend, potentially forming life-threatening rip currents as they break at the shore. Stay safe!

FIRE WEATHER

Issued at 339 AM AST Fri May 8 2026

Breezy conditions and the lack of significant cloud cover will also maintain an elevated fire danger risk, particularly across the southern coastal plains of Puerto Rico, where fuels continue to dry.

SJU WATCHES/WARNINGS/ADVISORIES

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