textproduct: San Juan

KEY MESSAGES

Updated at 234 PM AST Sat Jul 25 2026

* A wind surge ahead of an approaching tropical wave will continue to promote passing showers and breezy trade winds for the rest of today; local and diurnal effects are resulting in showers and t- storms over Puerto Rico.

* Shower and t-storm activity will increase late tomorrow into Monday as the arriving tropical wave interacts with an upper-level low, elevating the threat for urban and small stream flooding, as well as sustaining the potential for lightning and strong gusty winds.

* A Heat Advisory continues through 4 PM AST across urban and coastal areas of Puerto Rico as various areas without shower activity are reporting heat indices at or above 108 degrees.

* Moderate to locally fresh easterly winds will continue through the weekend, producing choppy seas and hazardous conditions for small craft across portions of the local waters.

* Up to a moderate risk of rip currents will continue this weekend across the local beaches.

Short Term(This evening through Monday)

Issued at 234 PM AST Sat Jul 25 2026

Variable weather conditions prevailed today, starting with some showers in the morning that were followed by cloudiness developing across the interior sections. Heat indices and temperatures climbed pretty quickly across the islands during the day, increasing up to 110 degrees across the north-central sections and southwestern coastal areas of the island. As a result, a Heat Advisory was issued for all coastal areas of Puerto Rico, including the Caguas vicinity, which remained in effect until 4 PM. Afternoon shower activity developed over the interior from Adjuntas to Mayaguez, while showers were also observed along the Fajardo area. Some strong thunderstorms were detected by the GOES across western interior sections, enhancing winds in excess of 25 mph according to radar velocity signals. By 2 PM, rainfall accumulations remained under one inch across the western interior, where the showers were most intense. Winds persisted from the east at 15 mph or less, with gusty conditions reported across the area and especially along coastal sections.

For the rest of the afternoon into the evening hours, weather conditions will remain variable under an easterly wind flow driven by surface high pressure across the Central Atlantic extending into the Caribbean area. Under this pattern, moisture will continue to linger with precipitable water values ranging between 1.5 and 1.7 inches. These conditions will remain suitable for persisting showers along interior sections as well as warm conditions across the islands. As the day progresses, temperatures are forecast to gradually decrease, settling in the low 80s across the San Juan metro area and in the mid-70s across the mountain sections, while winds remain from the east at 10 mph or less. At the mid-to-upper levels, stable conditions will persist across the region due to a strong mid-level ridge located north of the area and the unfavorable side of an upper-level low moving southward into the region.

By Sunday, the surface high pressure across the Central Atlantic will maintain easterly winds during the first part of the day while a much drier air mass builds over the area. Unlike previous days, global weather models indicate that the moisture associated with the next tropical wave has been delayed, now expected to reach the region early Monday morning. This wave has a positive tilt; therefore, the axis of the wave is expected to cross the islands early on Monday, with the main moisture field following shortly after, increasing showers and cloudiness. At the same time, an upper-level cut-off low will dig into the area late Sunday into Monday, positioning its divergent and highly favorable southeastern quadrant directly over the local islands. The combination of these upper-level dynamics and the positively tilted wave will significantly enhance shower and thunderstorm potential starting Monday, beginning across the U.S. Virgin Islands where an increase in both shower frequency and intensity is expected.

Long Term(Tuesday through next Friday)

Issued at 234 PM AST Sat Jul 25 2026

The latest model guidance continues to suggest above-normal precipitable water (PWAT) values exceeding 2.00 inches by the beginning of the long-term period, as moisture associated with a passing tropical wave continues to linger across the area. At the upper levels, an upper-level low will begin to migrate northwestward away from the region, providing some stability aloft that will be reflected in rising heights and warmer mid-level temperatures (at 500 mb). At the surface, a high-pressure system will continue to strengthen, resulting in breezy to locally windy east-southeasterly winds across the area.

Under this scenario, moisture content will remain above average and when combined with local effects and diurnal heating, will likely support fast moving showers during the morning hour across the windward areas of the islands, followed by afternoon convection across the interior and western portions of Puerto Rico. During this period, ponding of water on roads and in poorly drained areas is possible.

From Wednesday onwards, a drier airmass will filter into the region, dropping PWAT values below normal to around 1.30 inches. This drier airmass will be accompanied by low concentrations of Saharan dust through at least Saturday. Despite the expected drier pattern, patches of moisture embedded in the trade winds will continue to reach the region, bringing fast-moving, passing showers across portions of Puerto Rico and the U.S. Virgin Islands with minimal to no impacts. Normal to above-normal temperatures will persist across the area, with daytime highs remaining between the upper 80s and low 90s in coastal and urban locations. Residents and visitors are encouraged to stay hydrated and monitor local weather updates.

AVIATION

(18Z TAFS) Issued at 234 PM AST Sat Jul 25 2026

VFR conditions prevail. Easterly winds at 1015 kts with gusts up to 18 kts will diminish after 25/23Z, then pick up again from the east around 26/14Z. Afternoon SHRA/TSRA across western PR will continue to affect the vicinity of Mayaguez and TJBQ through 25/23Z, bringing brief MVFR/IFR conditions and mountain obscurations. For Sunday, VCSH/SHRA is forecast for TIST and TISX between 26/14Z and 26/18Z as low-level moisture increases ahead of an approaching tropical wave.

MARINE

Issued at 234 PM AST Sat Jul 25 2026

Moderate to locally fresh easterly winds will continue through the weekend, causing choppy seas and hazardous conditions for small craft across portions of the local waters. An improvement in seas is anticipated early next workweek as winds decrease. However, an approaching tropical wave will cause scattered showers and isolated thunderstorms to increase late tomorrow, Sunday into Monday. Saharan dust is expected to gradually diminish, though low to locally moderate concentrations will persist into early next week.

BEACH FORECAST

Issued at 234 PM AST Sat Jul 25 2026

Through the remainder of the weekend, beaches across northern and eastern Puerto Rico, St. Croix, Culebra, and Vieques will continue to experience a moderate risk of rip currents (life-threatening rip currents are possible in the surf zone). While beach conditions are projected to improve somewhat by midweek due to a gradual decrease in winds early next workweek, another increase in the rip current risk is anticipated later in the workweek due to strengthening easterly winds. Even in areas where the risk of rip currents is low, life-threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. Additionally, those visiting the beach should stay alert for heat and thunderstorms.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 4 PM AST this afternoon for PRZ001>005-007- 008-010-011.

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