textproduct: San Juan

KEY MESSAGES

Updated at 450 AM AST Thu Apr 9 2026

* A High Risk of Rip Currents is in effect for the northern coast of Puerto Rico and Culebra today and possibly through the weekend due to pulses of northerly swells.

* Small craft should exercise caution over mainly the offshore and nearshore Atlantic Waters, and the Mona Passage, due to seas of 5 to around 6 feet.

* Generally stable weather conditions are forecast, with isolated showers over windward areas and afternoon convection over mainly interior to W-NW PR through the rest of the week. An approaching trough will result in a wetter and more unstable pattern beginning early next week.

* For the U.S. Virgin Islands, generally fair weather conditions are expected through the rest of the week, with isolated showers from time to time.

* Normal to above-normal temperatures will persist through the rest of the week, prompting a limited heat risk.

Short Term(Today through Saturday)

Issued at 450 AM AST Thu Apr 9 2026

Since midnight, radar estimated rainfall accumulations showed minimal accumulations over interior, eastern and western sectors of Puerto Rico, as light showers moved over those areas. Official and unofficial stations have reported lows in the 70s across coastal areas, with some reaching 78 to 80 degrees, and in the low to upper 60s across interior PR. Patchy fog was also detected over areas of the interior. Current satellite derived precipitable water (PWAT) values indicate values at 1.65 to 1.80 inches (high end normal to above normal values) over the islands with higher values at around 1.90 over the northwestern and and southeastern waters as moisture continues to be steered towards the islands. As a broad surface high over the central Atlantic interacts with a frontal low over the western Atlantic, winds will back during the period to become more ESE to E. 925 wind speeds are forecast to continue up to around 15 kts, normal for this time of the year, however breezy continues are forecast at some lower elevation/coastal areas. This flow will continue to steer broad moisture fields towards the islands today and Saturday, and patches of both moisture and drier air tomorrow, Friday. Vertical available moisture will decrease as the period continues with 800 to 700 mb relative humidities staying at normal values and 700 to 500 mb relative humidities decreasing from above normal today to normal tomorrow and Saturday. Although some instability at the area (in part due to the frontal boundary and trough north of the area along with some trade wind perturbations reaching the area), subsidence aloft and warming 500 mb temperatures (mid level ridge) will serve to limit shower development. Galvez- Davison Index (GDI) values are forecast at up to 20 today and tomorrow and up to 30 on Saturday. Showers will continue to reach windward sectors each morning and night, with afternoon convection due to diurnal heating, sea breeze convection, and local effects forecast over mainly interior to W-NW PR, as well as possibly downwind of the local islands and El Yunque. Model guidance also suggests afternoon convection over W-NW PR today, prompting a limited flooding risk. Friday appears to be the day with least rain activity. A limited flooding risk is also forecast for Saturday due to afternoon convection over interior to W-NW PR. Patchy fog over areas of the interior will continue during the overnight hours. Low concentrations of Saharan Dust will persist over the area through the rest of the week. 925 mb temperatures are forecast to be near to above normal, with highs reaching the upper 80s to around 90 at urban and coastal areas. This pattern suggests a limited heat risk is possible, particularly today and tomorrow, Friday.

Long Term(Sunday through Thursday)

Issued at 450 AM AST Thu Apr 9 2026

A transition toward a wetter and more unstable pattern is expected beginning Sunday as a deep-layered trough approaches the region and interacts with above-normal moisture. Early in the period, conditions will still resemble a typical diurnal pattern, with passing morning showers across eastern Puerto Rico and the U.S. Virgin Islands followed by afternoon convection over western Puerto Rico. However, as the trough moves closer and moisture increases, shower and thunderstorm activity is expected to become more widespread from late Sunday into early next week. The most active period currently appears to be Monday into Tuesday, when deeper moisture and cooler temperatures aloft will support more organized convection. Thereafter, conditions should gradually trend toward near-normal by mid to late week, although lingering moisture may continue to support scattered shower activity. Confidence in this overall pattern is moderate, particularly regarding the timing and coverage of the wettest period.

The primary hazard will be an increasing risk of flooding, especially from Monday into Tuesday when more persistent and widespread showers and thunderstorms are expected. Periods of heavy rainfall may result in ponding of water on roadways, urban and small stream flooding, and isolated flash flooding where repeated activity develops. Thunderstorms will also pose a risk of frequent lightning and locally gusty winds. While impacts early in the period should remain localized, the potential for more widespread and impactful conditions increases early next week. Given the evolving pattern and moderate forecast confidence, residents and visitors should continue to monitor updates as details may change.

AVIATION

(06Z TAFS) Issued at 450 AM AST Thu Apr 9 2026

Mainly VFR conditions. Winds will gradually back to become more ESE to E at up to 10 knots through 09/13z, increasing to 10 to 17 kts after, with higher gusts and sea breeze variations. VCSH/-SHRA over the terminals. Around 09/17-22z SHRA/isolated TSRA possible near or at JBQ. Winds decreasing to light and VRB after 09/23Z.

MARINE

Issued at 450 AM AST Thu Apr 9 2026

Light to moderate east to southeasterly winds will prevail throughout the day. Winds will turn more easterly from late tonight and through the weekend as a broad surface high pressure builds from the Central Atlantic. A small, but long period northeasterly swell will linger across the Atlantic waters today. However, from late tonight through Friday, a 4 to 5 feet northwest to north swell will spread across the Atlantic waters and passages, building seas up to 6 feet. Therefore, small craft should continue to exercise caution. Another pulse of the northerly swell is expected on Sunday. By early next week, a frontal boundary and a pre-frontal trough will increase showers and thunderstorms across the regional waters.

BEACH FORECAST

Issued at 450 AM AST Thu Apr 9 2026

A series of small (2-4 ft), but long period northerly swells will increase the threat of life-threatening rip currents along the northern exposed beaches of the islands during the next few days. Therefore, a High Rip Current Risk was issued for the northern beaches of Puerto Rico and Culebra through at least late Friday night. By early Sunday, another pulse from the northerly swell is expected to reach local coastal waters of the islands, and the High Rip Current Risk could be extended for the same areas through the weekend. Across the USVI and Vieques, a moderate risk of rip currents is expected to prevail through the same period.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late Friday night for PRZ001-002- 005-008-012.

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