textproduct: San Juan

KEY MESSAGES

Issued at 244 PM AST Fri Jan 16 2026

* Deteriorating marine and coastal conditions are expected this weekend as a northerly swell combines with breezy winds, leading to hazardous seas and an increased risk of rip currents, especially along northern and northeast-facing beaches.

* A strengthening to moderate to locally breezy wind flow is forecast by this afternoon and will persist through the weekend. Secure loose outdoor objects and use caution in gusty wind conditions.

* Trade wind showers will continue, with a brief increase in rainfall activity possible during the afternoon hours, mainly across western Puerto Rico, resulting in wet roads and ponding in low-lying and poor drainage areas.

Short Term(This evening through Sunday)

Issued at 244 PM AST Fri Jan 16 2026

Mostly fair conditions persisted across the islands, with a few passing showers moving over portions of southeastern Puerto Rico. Winds continue to increase across the local area, with stations reporting maximum wind gusts between 24 and 29 mph over coastal areas and higher elevations. The forecast for today remains on track, with the highest chance of showers and isolated thunderstorms in the afternoon. According to the 12z RAOB, the moisture content remains high for this time of year, with PWAT values (1.58 inches) exceeding the 75th percentile (1.49 inches). Although the sounding reported 500 mb temperatures warmer than usual (around -3 degrees Celsius), the proximity of a deep-layered trough over the Hispaniola, diurnal heating combined with local effects, and sea breeze convergence could be enough for breaking the inversion cap and increasing the potential of thunderstorm activity. Hence, isolated thunderstorms cannot be ruled out. This activity should concentrate on portions of western Puerto Rico, and the most likely scenario remains as ponding of water over roadways, urban, and poorly drained areas, along with isolated minor flooding.

Variable and breezy conditions will persist in the short-term forecast. The surface high pressure over the Central Atlantic will strengthen, increasing the pressure gradient, and bringing breezy to windy conditions across the islands. Hence, coastal areas and higher elevations can expect higher wind gusts this weekend (between 26 and 38 mph). Current satellite-derived products show an area of drier air mass (PWAT between 0.7 and 1.0 inches) over the Leeward Islands, expected to filter into the region later tonight and limit shower activity. Nevertheless, the frequency of showers is expected to increase in the morning hours due to a patch of moisture moving across the CWA. Based on HIRES models, passing showers are expected to move across the U.S. Virgin Islands and eastern portions of Puerto Rico, with afternoon convection still likely over portions of western Puerto Rico. Nevertheless, rainfall accumulations in the afternoon will at most lead to ponding of water over roadways, urban, and poorly drained areas. In terms of lightning, the mid- level ridge should strengthen once again and linger north of the region, maintaining warmer than normal mid-level temperatures (around -4 degrees Celsius) and increasing stability aloft. Hence, the lightning risk will remain low. This weather pattern should prevail on Sunday as well.

Long Term(Monday through next Thursday)

Issued at 352 AM AST Fri Jan 16 2026

The latest model guidance indicates a transition toward a wetter and more unsettled pattern beginning Monday and continuing through much of the workweek. Precipitable water values are forecast to increase to around 1.75 inches, which is above normal for this time of year and supportive of additional rainfall activity, particularly by midweek. From Monday through Wednesday, a subtropical jet streak near 250 mb will enhance upper-level divergence and support the development of an induced surface trough, resulting in higher shower coverage across the forecast area as easterly to northeasterly low-level flow becomes established by midweek.

Tuesday may see some variability as guidance hints at a pocket of drier air moving south of the region. At this time, it remains unclear whether this drier air will reach the forecast area, and its potential influence on rainfall will continue to be monitored.

Wednesday currently appears to be the wettest and most unstable day of the long-term period. 500 mb temperatures near -7 degrees Celsius will promote greater vertical growth of convection, increasing instability and the potential for isolated thunderstorms, particularly during the afternoon hours. In addition, weakening low-level winds may allow showers to persist over the same areas for extended periods, potentially elevating the risk of localized flooding.

From Monday onward, 925 mb temperatures are expected to remain above normal. When combined with the increasing moisture, conditions may feel warmer than they actually are. While rainfall coverage and intensity may vary at times, each afternoon carries at least a limited flooding risk, primarily due to ponding of water on roads and in poorly drained locations.

AVIATION

(18Z TAFS) Issued at 244 PM AST Fri Jan 16 2026

Mainly VFR conds are expcd across all TAF sites. Aftn cnvtn across mountain ranges of PR will bring VCSH across all terminals through 16/22z, temporarily reducing CIGs. TSRA cannot be ruled, and AMDs may be required for JPS and JBQ. A patch of moisture will increase SHRA activity by 17/12z with passing showers across the TAF sites, reducing once again CIGs and VIS. Winds from the E will slightly weakened, btwn 8 - 10 kt, strengthening by 17/12-14z around 15 kt and gusts up to 30 kt.

MARINE

Issued at 244 PM AST Fri Jan 16 2026

Surface high pressure across the central Atlantic will continue to support gentle to moderate east to southeast winds tonight. By Saturday, model guidance continues to indicate strengthening east to northeast winds along with the arrival of a long-period northerly swell. This combination will result in building seas and increasingly choppy to rough marine conditions, leading to hazardous marine conditions across the regional waters from Saturday through the remainder of the weekend.

BEACH FORECAST

Issued at 244 PM AST Fri Jan 16 2026

The moderate risk of rip currents along all the northern-exposed beaches of Puerto Rico and the U.S. Virgin Islands will remain favorable through at least tonight. However, conditions are expected to deteriorate beginning Saturday and persist through the weekend.

Model guidance continues to suggest a northerly swell moving into the local waters, combining with rough seas generated by breezy conditions. This pattern will lead to increasingly large breaking waves and stronger nearshore currents, particularly along the north and northeast-facing beaches of Puerto Rico, including Culebra, as well as exposed beaches across the U.S. Virgin Islands.

As a result, a high risk of rip currents is expected to develop on Saturday and continue through the weekend, posing hazardous conditions for swimmers and beachgoers. Beachgoers are urged to exercise caution, follow guidance from local authorities, and avoid entering the water in areas under a high rip current risk.

For localized and updated risk levels, visit weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...Small Craft Advisory from 2 PM Saturday to 2 PM AST Monday for AMZ711.