textproduct: San Juan

KEY MESSAGES

Updated at 120 PM AST Thu Apr 30 2026

* Showers and thunderstorms are expected to cause urban and small stream flooding over the interior and northern Puerto Rico. Saturated soils and elevated river levels may worsen impacts on vulnerable areas.

* Across the U.S. Virgin Islands, mainly fair weather conditions will prevail with a few passing showers moving into the area from time to time.

* A gradual transition into drier and stable conditions is expected from late Friday onward, with limited shower activity.

* Warmer-than-normal temperatures will continue through the weekend, with heat indices reaching or exceeding 100F across urban and coastal areas.

Short Term(This afternoon through Saturday)

Issued at 120 PM AST Thu Apr 30 2026

Sunny to partly cloudy skies were observed across the U.S. Virgin Islands during the morning hours, while cloudy to partly sunny skies prevailed across Puerto Rico. Showers streamed from the Mona Passage into the Atlantic waters through the early morning hours, with mostly high clouds and light rain observed over portions of northwestern Puerto Rico. For the rest of this afternoon, locally induced showers with isolated thunderstorms are expected to develop over portions of the interior and north-central PR. Urban and small stream flooding is possible across these areas. In addition, light west to southwest steering winds could steer this activity into portions of west/northwest PR through the evening hours. Across the USVI, mostly fair weather conditions are expected to prevail in general, with low-level clouds and mostly light showers developing downwind of the islands this afternoon. High temperatures were from the mid-to upper-80s across the lower elevations of the islands to the upper 70s and low 80s across the higher elevations. Winds were from the east-southeast up to 12 mph with higher gusts at times and sea breeze variations across the western and southern coast of PR.

A drying trend is expected from late Friday and Saturday, as a surface high pressure strengthens north of the region, and a mid- to upper-level ridge build from the west, bringing drier air and more stable conditions in general across the region. The precipitable water content is expected to drop from 1.90 inches today to near 1.60 inches on Saturday. Having said that, locally induced afternoon showers are still expected to develop over the western interior of PR each afternoon, where the flood threat will remain elevated on Friday.

Long Term(Sunday through next Thursday)

Issued at 120 PM AST Thu Apr 30 2026

The long-term period will be dominated by generally tranquil, near- seasonal conditions for both Puerto Rico and the U.S. Virgin Islands. Surface high pressure over the central Atlantic will promote east to southeast winds at 8 to 15 mph through the period. Aloft, a ridging pattern will persist, supporting stable conditions. On Sunday, patches of moisture will maintain precipitable water (PWAT) values near seasonal levels, around 1.5 inches. This will support brief, passing showers across windward areas during the morning, followed by scattered afternoon showers and isolated thunderstorms across the northwestern quadrant of Puerto Rico. Flood risk will remain low and localized.

A drying trend will develop early next week, leading to improving conditions. Model guidance indicates PWAT values falling into the 25th percentile. In perspective, PWAT values are expected to be around 1.25 inches or less. Combined with a mid to upper-level ridge, this will enhance stability. The driest period is expected from Monday through Wednesday. Afternoon showers may still develop due to local effects and diurnal heating, but coverage will be limited and activity brief. Rain chances will range from 10 to 30 percent each afternoon across northwestern Puerto Rico. By Thursday, moisture will increase back to near-normal levels as patches of moisture arrive. At the same time, an upper-level trough will begin to amplify into the region, increasing instability and the potential for shower development.

Despite reduced rainfall, the main hazard will be the warm conditions that will likely persist across the islands. Temperature guidance at 925 mb, along with a prevailing east to southeasterly wind flow, suggests values will remain above normal throughout the forecast period. Daytime highs will range from the upper 80s to low 90s in coastal and urban areas, and from the upper 70s to mid-80s in higher elevations. Heat indices will reach the upper 90s to low 100s degrees F daily. A limited heat threat will persist for urban, coastal, and low-elevation areas. Residents and visitors should stay hydrated and limit prolonged sun exposure during peak heating hours.

AVIATION

(12Z TAFS) Issued at 120 PM AST Thu Apr 30 2026

SHRA/TSRA expected to develop over the interior and western PR thru 30/22z. This should cause mostly VCTS at TJSJ/TJPS/TJBQ. However, brief periods of MVFR to brief IFR conds cannot be ruled out at TJBQ with this activity. The 30/12z TJSJ sounding indicated ESE winds up to 12 kt blo 3000 ft.

MARINE

Issued at 120 PM AST Thu Apr 30 2026

A series of highs and frontal boundaries extending from the western into the Atlantic will prevail over the next few days. As a surface high pressure moving north of the region will increase the pressure gradient, strengthening winds and becoming moderate from the east. Showers and isolated thunderstorms will continue today across local Atlantic waters, leading to localized hazardous conditions for small craft. Pulses of a weak, long-period northerly swell will continue to spread across the Atlantic waters and local passages this evening, another arriving on Saturday, though seas should remain between 3 and 5 feet.

BEACH FORECAST

Issued at 120 PM AST Thu Apr 30 2026

No changes were introduced to the beach forecast. The small, long- period northeasterly swell continues to spread across local waters and passages. Current nearshore buoy observations report seas between 1 and 2 feet, with periods of 9 to 10 seconds, producing breaking waves around 3 to 5 feet. Hence, the moderate risk of rip currents will continue for the northern-exposed beaches of Puerto Rico, including Culebra, and for St. Thomas and St. John in the U.S. Virgin Islands. Another swell is expected to arrive by Saturday, but the risk should remain moderate for the next several days, though beachgoers must exercise caution as life-threatening rip currents are still possible along the surf zone.

For additional information and location-specific rip current details, please visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

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