textproduct: San Juan

KEY MESSAGES

Issued at 219 PM AST Sun Feb 1 2026

* An elevated flood threat continues through midweek. Periods of moderate to heavy rainfall may result in urban and small stream flooding, localized flash flooding, and minor landslides, especially across steep terrain. The risk increases late tonight through Tuesday. Residents and visitors should remain alert and avoid rivers, creeks, and flood-prone areas.

* While swell energy has temporarily diminished today, a strong north to northwesterly long-period swell will arrive Monday, producing very hazardous marine and coastal conditions. High Surf and High Rip Current Risk conditions are likely, with beach erosion and minor coastal flooding possible in vulnerable coastal areas.

* Marine conditions will deteriorate rapidly beginning Monday as increasing winds and building seas impact local waters. Small Craft Advisories are in effect, with additional marine zones likely to be added as hazardous seas develop.

* Isolated to scattered thunderstorms will continue through at least midweek, capable of producing frequent lightning, brief gusty winds, heavy rainfall, and reduced visibility over land and coastal waters.

* The U.S. Virgin Islands will remain on the drier side of the system this afternoon; however, shower coverage will increase late tonight and Monday, with the highest rainfall potential expected Monday night through Tuesday.

Short Term(This evening through Tuesday)

Issued at 219 PM AST Sun Feb 1 2026

Throughout the day, periods of sunny to partly cloudy skies and generally calm conditions prevailed across Puerto Rico and the U.S. Virgin Islands. A band of showers associated with a frontal boundary remained northwest of the region, extending across the western Atlantic waters and the Mona Passage. Non-official weather stations reported temperatures along the coastal areas in the upper 80s to low 90s, while temperatures across the higher terrain ranged from the upper 70s to low 80s. Winds were mainly from the south to southeast.

Tonight, rain chances will increase as the frontal boundary approaches the region, with the greatest impacts expected across western and northwestern Puerto Rico. As a result, the risk of flooding will rise across these areas tonight and remain elevated through at least midweek. Across the U.S. Virgin Islands, shower activity will be more prevalent during the morning hours.

From Monday into Tuesday, under a north to northeast low-level flow, shower and isolated thunderstorm activity will shift toward southern, southeastern, and eastern Puerto Rico, with some activity spreading into the San Juan metropolitan area. Periods of moderate to heavy rainfall will remain possible across the islands under continued moist and unstable conditions.

Overall, a wet and unsettled weather pattern is expected to persist across the region through at least Tuesday. This pattern is being driven by an approaching frontal boundary from the northwest, an upper-level polar trough, and a mid- to upper-level ridge positioned east of the islands. This synoptic setup will maintain a favorable environment for deep-layer instability and efficient rainfall, supported by persistent moisture transport from the Caribbean and precipitable water values remaining well above normal for this time of year, near or exceeding 2.25 inches. As the frontal boundary approaches and crosses the region, winds will gradually shift from southerly to northwesterly by the beginning of the workweek. Given this setup, the flooding risk will remain elevated across much of the region through Tuesday, with the potential for significant flooding, particularly across southern and eastern Puerto Rico. Expected impacts include rapid river rises, urban and small-stream flooding, potentially life-threatening flash floods, landslides in steep terrain, and locally gusty winds. Residents and visitors are urged to closely monitor weather updates and remain alert to changing conditions.

Long Term(Wednesday through next Saturday)

Issued at 448 AM AST Sun Feb 1 2026

The frontal boundary is expected to linger near the local area through midweek, as a weak area of high pressure rolls from the western Atlantic and passes just north of the area into the central Atlantic by the end of the workweek. This will slow and turn winds more easterly, and keep an overall higher moisture content over the area, particularly on Wednesday. Also, a short-wave trough will promote colder than normal 500 mb temperatures around minus 7/8C, which destabilizes the atmosphere and increase once again the likelihood of thunderstorms. Therefore, another unsettled weather day is expected across the islands, and due to the expected saturated soils, any additional period of excessive rainfall will lead to quick flooding. Lingering moisture and small variations on the 500 mb temperatures will promote shower and isolated thunderstorm development once again on Thursday. However, a drying trend is now expected on Friday and early Saturday, before the arrival of the next deep polar trough and associated frontal boundary during the weekend.

AVIATION

(18Z TAFS) Issued at 219 PM AST Sun Feb 1 2026

Mainly VFR conditions are expected to prevail across all TAF sites through the fcst pd. However, SHRA will affect portions of Puerto Rico and the U.S. Virgin Islands, resulting in brief periods of MVFR conditions at times. The greatest potential for MVFR conditions will be across TJPS, then shifting to TJBQ, TJSJ, TIST, and TISX after approximately 02/00Z. Isolated TSRA cannot be ruled out tonight into Monday, which may temporarily reduce visibility and ceilings.

MARINE

Issued at 219 PM AST Sun Feb 1 2026

Moderate southerly winds will continue through this afternoon ahead of an approaching frontal boundary. Winds will shift to the west and north late tonight into Monday as the front moves through the regional waters.

In the wake of the front, winds are expected to increase significantly, with sustained speeds of 20 to 25 knots and higher gusts through at least Tuesday. A strong north-northwesterly long- period swell will build into the local waters beginning Monday, resulting in very hazardous marine conditions, particularly across the Atlantic waters and passages. Seas are expected to build to 8 to 12 feet, with higher seas possible in exposed waters.

Scattered to numerous showers and isolated thunderstorms will continue across the regional waters, with thunderstorms capable of producing locally gusty winds, rough seas, and reduced visibility.

Small Craft Advisories are in effect beginning Monday morning, with additional marine zones likely to be added as conditions continue to deteriorate through midweek.

BEACH FORECAST

Issued at 219 PM AST Sun Feb 1 2026

Nearshore buoy observations indicate that northerly swell energy has diminished somewhat today, resulting in slightly reduced surf heights compared to earlier this morning. Despite this temporary decrease, hazardous marine and beach conditions persist, and a high risk of rip currents continues across all north-facing beaches.

Beginning Monday, a strong north-northwesterly long-period swell will build into the region and persist through at least midweek. This swell will result in rapidly increasing surf heights, powerful breaking waves, and very dangerous coastal conditions, especially along exposed Atlantic and northwestern coastlines. Peak impacts are expected Monday into Tuesday.

As a result, High Surf Advisories are very likely, along with a continued High Rip Current Risk. In addition, coastal flooding of low-lying and vulnerable shoreline areas is possible, and a Coastal Flood Advisory may be required as onshore flow and elevated tides combine.

Beachgoers should also remain alert for nearby thunderstorms, which may produce locally gusty winds, lightning, and sudden reductions in visibility, further increasing the risk for marine and beach activities. Beachgoers and mariners are urged to continue monitoring forecast updates and heed all local advisories, warnings, and guidance from lifeguards and local officials as conditions deteriorate.

For localized and updated rip current information, visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk until 6 PM AST this evening for PRZ001-002- 005-008-010-012.

VI...High Rip Current Risk until 6 PM AST this evening for VIZ001.

AM...Small Craft Advisory from 6 AM Monday to 2 AM AST Thursday for AMZ711-712-741-742-745.