textproduct: San Juan

KEY MESSAGES

Updated at 223 PM AST Thu Apr 9 2026

* Hazardous marine and coastal conditions will develop as a north-northwesterly swell spreads across the Atlantic waters, leading to dangerous seas and rip currents.

* A wet weather pattern from Sunday into the upcoming workweek will increase the potential for showers and lightning across the region. Therefore, an increase in flood risk is forecast. While it is too early to determine how much rainfall will fall, the most likely scenario is for 1 to 3" each day, and very isolated higher amounts.

* A limited heat threat will persist across the islands tomorrow, with warm conditions expected mainly in coastal areas.

* Stable weather conditions are expected to prevail across the U.S. Virgin Islands through the short-term period.

Short Term(This evening through Saturday)

Issued at 223 PM AST Thu Apr 9 2026

During the morning hours, partly cloudy skies prevailed across the region, with only a few light showers and minimal accumulations. Winds have been mainly from the east to southeast at around 10 to 15 mph, with occasional higher gusts. Daytime maximum temperatures are ranging from the mid-80s to the low 90s across low-elevation, urban, and coastal areas, and from the upper 70s to the low 80s in the mountainous regions. Across the USVI, temperatures are fluctuating in the upper 80s. Heat indices have reached the low 100s, consistent with a limited heat threat.

For the rest of the afternoon, scattered showers are expected to develop across west-central into northwestern Puerto Rico. A limited flood risk persists due to the possibility of localized ponding of water on roads and in poorly drained areas.

In general, a broad surface high over the central Atlantic continues to interact with a frontal low over the western Atlantic, as a result, winds will gradually back and become more easterly during the short-term period. At mid-levels, ridging is prevailing, supporting stability and preventing showers from strengthening. Additionally, according to the latest precipitable water (PWAT) satellite-derived imagery, an air mass with values around 1.5 inches will continue to dominate across the region through Saturday, which is considered normal for this time of year. The 250 mb heights, 500 mb temperatures, and 700500 mb relative humidity values will remain above normal, contributing to increased stability. As a result, for tomorrow (Friday), a generally stable weather pattern is expected, with no flood threat anticipated at this time. Only a few isolated afternoon showers are expected over northwestern Puerto Rico due to local effects, with no significant impacts. By Saturday, showers will continue to affect windward sectors during the night and morning hours, followed by afternoon convection across northwestern Puerto Rico. This will maintain a localized, limited flood risk across the northwestern quadrant of the island.

In the short term, warmer-than-normal temperatures will persist, as reflected in the 925 mb temperature forecasts, which remain near the 75th percentile over the next few days. As a result, a limited heat risk will continue across low-elevation and urban areas of the islands.

Long Term(Sunday through next Wednesday)

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.

For additional information, please refer to the Hydrologic Outlook (ESFSJU).

AVIATION

(18Z TAFS) Issued at 223 PM AST Thu Apr 9 2026

VFR conditions will persist for all TAF sites during the period. Some brief SHRA with VCTS is possible between 09/18Z -09/21Z at TJBQ, reducing VIS and resulting in some lower cigs affecting the FL020 to FL030. Some VCSH are possible across other areas. Winds will persist from the east at 15 knots with sea breeze variation, diminishing at 10/00Z, becoming more VRB and light, and increasing again at 10/14Z from the E.

MARINE

Issued at 223 PM AST Thu Apr 9 2026

A broad surface high pressure, in combination with a frontal boundary just to the northwestern Atlantic, will induce moderate easterly winds across the local waters. Wave heights for tonight have fluctuated between 3 and 4 feet; however, deteriorating marine conditions are expected as a northwest to north swell spreads across the local waters, increasing seas from tomorrow into the upcoming weekend. Therefore, small craft should continue to exercise caution. From Sunday onward, a deep upper-level trough and the associated surface trough will enhance thunderstorm activity, resulting in localized hazardous marine conditions. Mariners can expect periods of gusty winds and reduced visibility in and around showers and thunderstorms. Mariners are urged to stay tuned for further updates.

BEACH FORECAST

Issued at 223 PM AST Thu Apr 9 2026

A small, long-period swell will continue to result in a high risk of rip currents across all northern and northeastern coastal areas of Puerto Rico, including Culebra. Another northwest to north long-period swell, with wave heights of 4 to 5 feet as indicated by buoy 41046, will further reinforce hazardous conditions. Therefore, large breaking waves will lead to life-threatening rip current conditions for the rest of the week and into the upcoming weekend. A moderate risk of rip currents will remain in place for the southern coastal areas and some western sections as the swell migrates southward into the local waters. Beachgoers are strongly urged to remain out of the water, especially along exposed northern and northeastern beaches. Conditions may vary locally, but even experienced swimmers can be caught in dangerous rip currents under this pattern. For more detailed information, please visit www.weather.gov/sju/marine

SJU WATCHES/WARNINGS/ADVISORIES

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

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