textproduct: San Juan

KEY MESSAGES

Updated at 225 AM AST Thu Jun 4 2026

* Another area of Saharan dust will move across the region today, resulting in hazy skies and reduced visibility at times.

* Passing showers will affect eastern Puerto Rico during the morning, followed by isolated afternoon convection across northwestern Puerto Rico.

* Warmer conditions are expected from Friday into the weekend. Heat- related impacts may affect vulnerable populations, so stay hydrated and limit prolonged outdoor activities.

* A moderate risk of rip currents will continue across most local beaches. Beachgoers should remain cautious when entering the water.

Short Term(Today through Saturday)

Issued at 225 AM AST Thu Jun 4 2026

Variable weather conditions prevailed across the local islands this evening as patches of low-level moisture moved across the region. Isolated to brief scattered showers developed across portions of eastern Puerto Rico and the surrounding waters, with additional passing showers expected through the overnight hours and around midnight across eastern Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands. As of 2 AM AST, rainfall accumulations were near an inch according to the radar rainfall estimates. Overnight temperatures will remain in the upper 70s to lower 80s along coastal areas, while cooler conditions are expected across the higher elevations and interior sections. Winds will continue from the east-southeast overnight, increasing the velocity near early morning.

A much drier and more stable weather pattern is forecast across the islands today. At the surface, a broad high pressure system over the central Atlantic combined with a surface low over the western Atlantic will maintain east-southeasterly winds across the region, promoting the advection of a drier air mass with precipitable water values ranging between 1.18 and 1.30 inches, nearly two standard deviations below normal for this time of year. Aloft, northwesterly flow around 250 mb will support stable atmospheric conditions, limiting vertical shower development. In addition, the NASA Goddard Earth Observing System Model continues to indicate a light concentration of Saharan dust particles across the region, resulting in hazy skies and suppressing widespread shower activity. As a result, rainfall activity is expected to remain limited, with only brief passing showers across windward sectors and isolated afternoon convection across portions of western Puerto Rico. Meanwhile, the east-southeast wind flow will continue to promote warm conditions, particularly across northern and western Puerto Rico, where heat indices will stay in the low 100s, but vulnerable persons can be affected during the day; stay well hydrated.

Friday through Saturday, stable conditions will persist due to a zonal flow aloft across the northeastern Caribbean. Meanwhile, at the surface, more easterly winds remain driven by a broad surface high pressure system over the central Atlantic. An increase in the pressure gradient will result in breezy conditions at times, especially across coastal areas and local waters. PWAT values are forecast to gradually increase to near climatological normals by Friday and Saturday, supporting a slight increase in shower activity compared to Thursday. At the same time, warmer temperatures at 925 mb will continue to support above-normal temperatures and elevated heat indices across lower elevations and urban areas. Heat indices could approach the 105 to 111 degrees across portions of northern and western Puerto Rico during the afternoon hours, particularly on Friday and Saturday. Overall, a typical weather pattern is forecast through Saturday, with passing showers moving across eastern Puerto Rico and the U.S. Virgin Islands during the overnight and morning hours, followed by the development of afternoon showers across western Puerto Rico.

AVIATION

(06Z TAFS) Issued at 225 AM AST Thu Jun 4 2026

VFR conditions are expected across all TAF sites through the period. Winds will remain from the E-SE at 10 kt, increasing after 04/15Z with occasional gusts. Cloud patches moving across the eastern Caribbean will promote VCSH and -RA near and around TJSJ, TIST, and TISX during the morning hours. Brief reductions in VIS, particularly across the USVI terminals, due to haze. Localized SHRA development is expected across the NW quadrant, bet 04/18Z and 04/21Z, resulting in some VIS reduction and lower ceilings.

MARINE

Issued at 225 AM AST Thu Jun 4 2026

A broad surface high pressure over the central Atlantic will continue to promote moderate to fresh east to southeast winds and choppy seas across the regional waters through the remainder of the workweek. The small northerly swell will continue to subside today, with additional small pulses expected through the end of the week. Seas will remain between 2 and 4 feet nearshore and 5 to 6 feet offshore, occasionally higher. Small craft should continue to exercise caution, especially offshore. A lingering moisture patch will support passing showers today, with activity gradually decreasing as moderate Saharan dust spreads across the region, leading to hazy conditions into Friday.

FIRE WEATHER

Issued at 225 AM AST Thu Jun 4 2026

The fire weather threat for today remains low, meaning some isolated fire conditions remain possible, particularly over the southern coastal areas of PR.

SJU WATCHES/WARNINGS/ADVISORIES

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