textproduct: San Juan

KEY MESSAGES

Updated at 257 PM AST Sun May 10 2026

* Breezy conditions and a limited heat threat will persist across many coastal and urban areas of the islands.

* Periods of passing showers will continue to affect windward sections of the islands, followed by locally induced afternoon showers over western Puerto Rico each day.

* Across the U.S. Virgin Islands, breezy conditions and occasional trade wind showers are expected. Highs reaching the upper 80s to lower 90s across urban and coastal locations.

* A moderate risk of rip currents will continue along the north and east-facing beaches of Puerto Rico, Culebra, and the U.S. Virgin Islands.

Short Term(This evening through Tuesday)

Issued at 257 PM AST Sun May 10 2026

Mostly tranquil conditions have persisted this Sunday, with the exception of a few passing showers across the U.S. Virgin Islands and portions of Puerto Rico. Breezy to windy conditions have been observed, with peak gusts ranging from 25 to 35 mph, as recorded at several official airport stations. Daytime highs have generally ranged from the mid to upper 80s, with isolated locations reaching the low 90s in urban and coastal areas of Puerto Rico and the USVI, and the low 80s across higher elevations.

The forecast remains generally on track. The dominant feature through early this upcoming week will continue to be mid-level ridging and a generally dry air mass over the region. Strengthening surface high pressure over the central Atlantic will promote moderate to fresh easterly to east-southeasterly winds around 15 to 20 knots, with higher gusts near coastal areas. Current satellite-derived precipitable water (PWAT) values range between 1.30 and 1.45 inches, below the seasonal average. For the rest of the afternoon, isolated to scattered trade wind showers will continue to move at times with occasional patches of moisture and locally induced activity. No significant flooding is expected.

From Monday afternoon through Tuesday, a slight increase in moisture is anticipated, with PWATs rising toward 1.75 inches, approaching the climatological average values. However, this moisture will remain mostly confined to lower levels. The mid-to- upper levels will stay exceptionally dry, with 700 to 500 mb relative humidity frequently dropping below 40%, and overall forecasted lapse rates remain unfavorable for deep convection. Consequently, significant thunderstorm development is unlikely. Any rainfall is expected from brief patches of slightly higher low-level moisture moving across the U.S. Virgin Islands and eastern Puerto Rico during overnight and early morning hours. By the afternoon, daytime heating and local effects may trigger scattered, localized showers over the interior and western municipalities of Puerto Rico. Overall rainfall accumulations are expected to be light, as showers should move quickly.

The primary hazard continues to be heat. Current 925 mb temperature guidance indicates a steady diurnal warming trend throughout the period. This persistent warm air mass, combined with available surface moisture, will result in daytime highs in the upper 80s to lower 90s across lower elevations, urban areas, and coastal plains. Heat indices may exceed 100 degrees F during peak afternoon hours. Residents and visitors are strongly encouraged to stay hydrated and limit sun exposure during the hottest part of the day.

Long Term(Wednesday through Sunday)

Issued at 310 AM AST Sun May 10 2026

A drier to seasonal weather pattern is anticipated over the long- term forecast. A broad surface high pressure is expected to linger over the Central Atlantic, promoting E-SE winds through most of the period. Additionally, a mid-level ridge will linger through most of the period, maintaining warmer than normal temperatures (500 mb temperatures fluctuating between -4 and -5 degrees Celsius), promoting subsidence and stability aloft. From Wednesday through Friday, patches of moisture will move from time to time, as the latest model guidance suggests an increase in moisture content (PWAT values between 1.5 and 1.75 inches). Passing showers are likely overnight into the morning hours over windward sections of the islands, with shallow afternoon convection in the western/northwestern section of Puerto Rico. Although shower activity may not lead to significant flooding impacts, localized areas can expect puddles over the roads and may become hazardous for drivers. By Saturday and Sunday, another surface high pressure moving over the Western Atlantic, and the high over the Central Atlantic may induce a col region north of the region, weakening the pressure gradient and winds. Due to local effects, combined with diurnal heating and sea breeze convergence, afternoon showers, particularly over interior and western Puerto Rico, may become stationary, increasing flooding potential. Ponding of water over roadways and poorly drained areas can be expected given these conditions, along with minor flooding. Isolated thunderstorms, on the other hand, cannot be ruled out.

Under an east-southeasterly wind pattern, warmer-than-normal temperatures are expected during the long-term forecast. Combined with the available moisture content, heat indexes will likely surpass 100 degrees and even meet Heat Advisory Criteria. Residents and visitors are encouraged to stay tuned for further updates, as these warm to hot conditions can affect most individuals sensitive to heat.

Based on the latest NASA DUex product, minor concentrations of SAL may reach the CWA on Wednesday, but may affect people sensitive to these particles.

AVIATION

(18Z TAFS) Issued at 257 PM AST Sun May 10 2026

Mainly VFR conditions are expected to prevail. Quick moving - SHRA/VCSH steered by breezy E to ESE winds will continue to affect most terminals through 10/23z and eastern and southern terminals thereafter. This can promote brief MVFR conditions. E to ESE winds will continue at 16-22 kts, with higher gusts up to 24 to 30 kts, winds will decrease, becoming lighter and variable after 11/00Z, picking up again after 11/13z with sea breeze variations.

MARINE

Issued at 257 PM AST Sun May 10 2026

A surface high pressure over the central Atlantic will promote moderate to locally fresh east to southeast winds across the regional waters through at least midweek, decreasing somewhat after. Seas will range between 3 and 5 feet, with occasional seas up to 6 feet. A small long-period northeasterly swell is also expected to arrive by midweek and spread across local waters. Choppy seas will continue as sustained winds of 15 to 20 knots, with occasionally higher gusts persist. Small craft are urged to exercise caution across most local waters.

BEACH FORECAST

Issued at 257 PM AST Sun May 10 2026

Up to a moderate risk of rip currents (life-threatening rip currents are possible in the surf zone) is forecast to continue tonight and tomorrow along the north, east, and southeast-facing beaches of Puerto Rico, Culebra, Vieques and St. Croix. A low risk of rip currents will continue elsewhere. However, even if the risk for rip currents is low, life-threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. A similar pattern will continue into next week as breezy conditions persist. A small long-period northeasterly swell is expected to arrive by mid-week and spread across local waters, resulting in in breaking waves of up to 4 to 5 feet, occasionally higher at times. For additional information, visit: weather.gov/beach/sju.

If you become caught in a rip current, yell for help. Remain calm, do not exhaust yourself and stay afloat while waiting for help. If you have to swim out of a rip current, swim parallel to shore and back toward the beach when possible. Do not attempt to swim directly against a rip current as you will tire quickly.

FIRE WEATHER

Issued at 257 PM AST Sun May 10 2026

An elevated fire threat continues through this afternoon, particularly across the southern coastal plains of Puerto Rico, as a result, the Fire Danger Statement remains in effect. Rainfall has been very limited along the southern sections, and a dry air mass over the region has allowed relative humidity to drop to critical fire weather levels. RAWS stations have recorded relative humidity in the upper 40s to low 50s, along with sustained winds of 15 to 20 mph and gusts up to 30 mph. Additionally, KBDI values remain elevated, especially in Cabo Rojo. These conditions favor the rapid spread of wildfires across the southern coastal plains.

Fire management partners are urged to remain vigilant, as similar conditions are expected to persist in the coming days. The issuance of additional Fire Danger Statements (RFDSJU) cannot be ruled out.

SJU WATCHES/WARNINGS/ADVISORIES

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