textproduct: San Juan

Short Term(This evening through Sunday)

Issued at 159 PM AST Fri Jun 5 2026

Today was warm to hot across Puerto Rico and the U.S. Virgin Islands due to an east-southeast wind flow, above-normal temperatures, and ample moisture. Heat indices ranged from 98 to 107 degrees Fahrenheit, with higher values in urban and poorly ventilated areas. Hazy skies resulted from moderate levels of Saharan dust. Winds were generally 10 to 20 mph, with local gusts higher. Temperatures were in the upper 80s to lower 90s in St. Croix, the San Juan metropolitan area, and parts of southwestern Puerto Rico. Showers developed in northern Puerto Rico, leading to a Flood Advisory for Vega Baja until 2:45 PM AST.

In addition to the above-normal heat indices, showers will continue, with some isolated thunderstorms possible for the rest of this afternoon and evening in the interior and northwestern sections of Puerto Rico, potentially causing heavy rainfall, roadway ponding, and urban flooding. Other areas will see partly to variably cloudy skies and warmer-than-normal temperatures.

Tonight through Saturday morning, fair weather with warmer-than- normal minimum temperatures is anticipated, with passing showers embedded in the winds affecting the U.S. Virgin Islands and eastern Puerto Rico. Moderate dust levels will create hazy skies and limit cooling. Breezy east-southeasterly winds will bring occasional moisture, leading to brief showers overnight and morning hours, followed by afternoon thunderstorms in western Puerto Rico.

A weak tropical wave is forecast to move through the eastern Caribbean on Sunday, increasing moisture availability and enhancing shower and thunderstorm development across the local area. However, abundant dry air and Saharan dust surrounding the wave should limit the potential for widespread flooding. Even so, localized ponding of water, urban flooding, and a few stronger thunderstorms cannot be ruled out, particularly during the afternoon hours across western Puerto Rico. Behind the wave, another significant Saharan Air Layer intrusion is expected to arrive Sunday night and persist into early next week, resulting in hazy skies, reduced visibility at times, and a return to more limited rainfall activity.

The excessive heating will continue throughout the weekend.

Long Term(Monday through next Thursday)

Issued at 159 PM AST Fri Jun 5 2026

A fairly persistent trade wind pattern is forecast to continue through the long-term period, with Atlantic high pressure maintaining an easterly to east-southeasterly low-level flow across the northeastern Caribbean. Winds will remain breezy at times on Monday, especially near coastal areas, but the pressure gradient should relax through midweek, allowing winds to become lighter. A modest increase in trade wind speeds is possible again late in the week.

Lingering moisture from the wetter pattern expected on Sunday will keep Monday somewhat active. However, a moderate concentration of Saharan dust is expected Monday into Tuesday, which may limit shower intensity at times by promoting a drier and more stable air mass aloft. This will also lead to hazy skies and reduced visibility, especially across coastal waters and exposed areas. Even so, low- level moisture should remain sufficient to support passing showers across eastern Puerto Rico and the U.S. Virgin Islands during the overnight and morning hours, followed by isolated to scattered afternoon showers across western Puerto Rico.

A relative minimum in moisture is expected from Tuesday into Wednesday. During this time, precipitable water values trend closer to climatology, and mid-level moisture remains limited. This should result in a more typical and somewhat quieter trade wind pattern, with brief morning showers across windward areas and only localized afternoon convection across western Puerto Rico. Overall rainfall amounts should remain light to moderate and mostly confined to areas where sea breeze and local effects enhance shower development.

By late Wednesday and continuing into Friday, moisture is forecast to gradually increase again as shallow patches embedded in the trades move across the region. The available moisture, along with local and diurnal forcing, should lead to a gradual uptick in shower coverage. Passing showers will be more likely across windward sections during the nighttime and morning hours, followed by scattered afternoon showers and a few isolated thunderstorms across western and interior Puerto Rico. The wetter trend should persist into Friday, though the overall pattern still favors intermittent activity rather than a widespread rainfall event.

Temperatures near 925 mb remain close to climatology, suggesting seasonable daytime highs; however, heat indices may still reach elevated levels across coastal and urban locations during breaks in cloud cover and rainfall.

AVIATION

(18Z TAFS) Issued at 159 PM AST Fri Jun 5 2026

Mainly VFR conditions throughout the period. ESE winds to continue up to around 15 kts with higher gusts. -SHRA/TSRA developing over northern PR and can affect northern terminals, these can promote brief MVFR conditions over northern terminals through 05/22Z. ESE winds will decrease to around 10 kts after 05/23Z, increasing again after 05/13Z. Passing -SHRA will continue to reach windward sectors from time to time.

MARINE

Issued at 159 PM AST Fri Jun 5 2026

A strong Atlantic high-pressure system will maintain a tight pressure gradient across the northeastern Caribbean through much of the forecast period, supporting fresh to strong easterly winds and choppy to rough seas across the regional waters, especially the offshore Atlantic waters and Caribbean Passages. A weak tropical wave will cross the local islands on Sunday, increasing shower activity and isolated thunderstorms. Hazy skies associated with a Saharan Air Layer will persist across the region, though marine visibilities should generally remain at 6 nautical miles or greater.

BEACH FORECAST

Issued at 159 PM AST Fri Jun 5 2026

The breezy to locally windy conditions will continue throughout the weekend and next week across the region, maintaining a moderate risk of life-threatening rip currents along most local beaches, particularly on north- and east-facing coastlines. Therefore, beach visitors are urged to swim only at beaches with lifeguards on duty, remain aware of surf conditions, and avoid venturing too far from shore, as life-threatening rip currents are possible across most of the region.

FIRE WEATHER

Issued at 159 PM AST Fri Jun 5 2026

Based on the observed fire weather conditions, we expect a low to moderate fire danger risk. Please stay tune for further updates.

SJU WATCHES/WARNINGS/ADVISORIES

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