textproduct: San Juan

KEY MESSAGES

Updated at 300 AM AST Sat Apr 25 2026

* Moderate rip current risk will persist along north-facing and exposed beaches, with locally hazardous marine conditions possible at times.

* A warming trend continues, with heat indices near or above 100F possible, especially in coastal and urban areas.

* Favorable weather conditions today through early Sunday, with limited shower activity; conditions deteriorate late Sunday into early next week with increasing flooding and lightning risks.

* Across the U.S. Virgin Islands, passing showers increase tonight into early next week along with warmer conditions; impacts remain localized but may increase early next week.

Short Term(Today through Monday)

Issued at 300 AM AST Sat Apr 25 2026

An evolving pattern will persist across the northeastern Caribbean, influenced by a distant surface trough north of the region and weak low-pressure perturbations across the western Atlantic. In combination with high pressure over the central Atlantic, this will support a predominantly southerly low-level flow. Aloft, weak troughing lingers today before gradually lifting. Overall, limited moisture depth will restrict vertical development through much of the weekend.

Locally, a patch of deeper moisture moved across the area overnight, supporting clusters of showers across southern Puerto Rico and a persistent band extending northward from near St. Croix across eastern Puerto Rico into the Atlantic waters. In its wake, a drier-than-normal air mass will move in this morning, leading to decreasing shower activity after sunrise. Afternoon convection will develop over the interior, drifting north to northeast today, then north on Sunday, remaining mostly shallow. By Monday, increasing moisture will support deeper convection, favoring the interior to north-northwest. Winds will be light to gentle from the south with sea breeze variations, and temperatures will trend above normal.

For today, no distinctive hazards are expected, but conditions should still be monitored for changes. On Sunday, a limited flooding risk and isolated thunderstorms are possible during the afternoon, along with increasing heat. By Monday into Monday night, a surge of deeper moisture will bring an elevated risk of flooding and lightning, with more widespread and efficient rainfall expected.

Long Term(Tuesday through Saturday)

Issued at 300 AM AST Sat Apr 25 2026

The forecast remains on track as abundant moisture from the Caribbean Sea streams into the region. This influx is driven by an approaching mid-to-upper-level trough from the west and an induced surface trough, both of which are significantly increasing local instability. Meanwhile, a dominant surface high pressure across the central Atlantic will maintain a light to variable south- southeasterly wind flow through most of the period.

Under this pattern, there is an enhanced potential for strong showers and thunderstorms on Tuesday. Scattered showers are expected across the U.S. Virgin Islands and eastern Puerto Rico during the morning, followed by vigorous afternoon convection across the interior and northern Puerto Rico, including the San Juan metro area. Recent analysis shows precipitable water (PWAT) values well above climatological values, peaking near 2.25 inches. While moisture levels will decrease slightly by Wednesday to between 1.75 and 2.00 inches, they remain unseasonably high. This unstable environment will promote daily showers and isolated thunderstorms, particularly during the afternoon hours over northern and interior Puerto Rico, as the upper-level trough deepens over the northeastern Caribbean. A gradual improvement in weather conditions is expected by the end of the workweek as drier air begins to filter in.

Warm to hot conditions will persist throughout the week due to the prevailing south-southeasterly flow. Temperatures at the 925 mb level are forecast to remain well above normal through Friday. Maximum surface temperatures will range from the upper 80s to low 90s in coastal and urban areas, and the low to mid-80s in higher elevations. Due to the combination of high humidity and southerly winds, heat indices will likely surpass 100F daily. Residents and visitors are strongly encouraged to prioritize hydration and limit prolonged sun exposure to remain safe during this period of excessive heat.

AVIATION

(06Z TAFS) Issued at 300 AM AST Sat Apr 25 2026

VFR will prevail at all TAF sites. VCSH thru 25/13Z at TJSJ/TJPS/USVI, brief CIG/VIS reductions possible (mainly TISX). Aft 25/1823Z, VCSH/-SHRA fm interior PR drifting NNE, mainly TJSJ vcnty, iso near TJBQ. MVFR brief/limited. Aft 25/23Z, VCSH returns to USVI ovrnght. No sig ops impacts expected. Winds lgt SE, bcmg VRB ovr PR, then inc to 512 kt aft 25/1214Z w/ sea breeze.

MARINE

Issued at 300 AM AST Sat Apr 25 2026

A frontal boundary meandering north of the region will continue to lift further away, while a weak surface high over the southwestern Atlantic shifts east into the central Atlantic during the weekend. This pattern will promote light to moderada southerly winds today, before easing again through early next week. A small, long-period NNE swell is expected to arrive today with additional pulses expected early in the workweek with limited impacts. Overall, marine conditions will gradually improve and remain below small craft advisory criteria.

BEACH FORECAST

Issued at 300 AM AST Sat Apr 25 2026

A moderate risk of rip currents is expected to prevail across all north-facing beaches of the islands through early next week. This means that life-threatening rip currents are possible in the surf zone. The risk of rip currents will remain low in the south-facing beaches of Puerto Rico and the U.S. Virgin Islands. A series of long- period NNE swells will spread across the Atlantic waters and passages through early next week. Although seas are expected to remain around 4 feet or less, these long-period swells could still increase the risk of life-threatening rip currents along the Atlantic coastline of the islands.

SJU WATCHES/WARNINGS/ADVISORIES

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