textproduct: San Juan

KEY MESSAGES

Issued at 303 AM AST Tue Mar 24 2026

* A moderate rip current risk is in effect across the north coast of Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands. However, marine conditions are expected to gradually improve, with more favorable seas across the local waters.

* Showers are expected today, mainly across the interior and western Puerto Rico. There is a limited risk of minor urban and low- lying flooding, as well as a localized limited risk of isolated lightning.

* Weather conditions will begin to deteriorate from Thursday into Friday, transitioning to a wetter pattern across the islands as moisture and instability increase.

* In the U.S. Virgin Islands, variable weather conditions are expected, with limited, short-lived shower activity.

Short Term(Today through Thursday)

Issued at 303 AM AST Tue Mar 24 2026

Similar to previous nights, mostly cloudy skies prevailed across most of the forecast area. Light to moderate shower activity was observed across some north-central areas for early morning hours, diminishing at 2 AM, specifically affecting municipalities from Arecibo to Vega Alta. The shower activity was light and did not result in significant rainfall accumulations; therefore, no flooding problems were reported. Minimum temperatures overnight were slightly below normal; across coastal areas, temperatures fluctuated between the low to mid 70s, and in the mountainous areas, between the upper 50s and the lower 60s.

A variable weather pattern will prevail across Puerto Rico and the U.S. Virgin Islands through midweek, followed by a transition to more unsettled conditions by Thursday. Today, a weak surface perturbation moving across the region will promote a gradual increase in moisture, with precipitable water (PWAT) values rising from around 1.5 to 1.6 inches, as indicated by GOES imagery. This feature will interact with a high-pressure system over the central Atlantic, resulting in northeasterly winds gradually veering more easterly by the afternoon. Despite the increase in low-level moisture, mid- to upper-level conditions will remain relatively stable, with 500 mb temperatures ranging between -5 and -6 C. However, a jet streak of around 85 mph at upper levels will support some degree of vertical development, enhancing shower growth where local effects are present. As a result, expect a variable weather pattern, with passing showers affecting northeastern Puerto Rico and the U.S. Virgin Islands during the morning hours, followed by localized convection along the Cordillera Central and western interior during the afternoon. Although conditions will generally remain unfavorable for widespread thunderstorm activity, one or two isolated thunderstorms cannot be ruled out, particularly with the heaviest showers. On Wednesday, similar conditions will persist, although a more established easterly wind flow and slightly reduced moisture content are expected, with PWAT values decreasing to around 1.5 inches according to global model guidance. This will likely result in a relative decrease in shower coverage and intensity, making Wednesday the most stable day of the period. Still, brief passing showers across windward areas during the morning and isolated afternoon convection across the interior and western Puerto Rico cannot be ruled out.

By Thursday, weather conditions are forecast to deteriorate as a mid- to upper-level tilted trough approaches just north of the islands. This feature will exacerbate instability and increase moisture content, with PWAT values rising to 1.7-1.85 inches. Additionally, colder temperatures aloft will further support convective development. At the surface, easterly winds with occasional southeasterly variations will prevail, promoting streamer-type activity affecting the San Juan metropolitan area during the morning hours, followed by more active afternoon convection across the northwestern quadrant of Puerto Rico. This pattern will increase the potential for heavy rainfall, leading to hazardous driving conditions and the possibility of urban and small-stream flooding, particularly during the afternoon hours. Residents and visitors are encouraged to stay informed on the latest forecasts, especially toward Thursday, when the risk of flooding impacts is expected to increase.

Long Term(Friday through Tuesday)

Issued at 303 AM AST Tue Mar 24 2026

As mentioned previously, Friday is expected to be the wettest day of the period. Moisture is expected to remain elevated on Friday, with precipitable water (PW) values generally in the 1.50 to 1.80 inch range, which is above normal for late March. Increased low-level moisture, along with a weak mid to upper-level trough near the region will support widespread cloudiness and periods of showers. Temperatures near 500 mb are forecast to remain around -6 to -8 degrees C, indicating moderate instability that may support occasional moderate showers. However, widespread organized convection is not anticipated. Enhanced cloud cover should limit daytime heating, keeping high temperatures near typical seasonal values. Winds will begin increasing on Friday, with the highest values around 15 to 20 knots during the weekend.

A gradual drying trend is expected through the weekend as precipitable water values decrease toward near-normal and even below normal values for this time of the year. While a few showers may still filter across the island from time to time accumulations should not be significant. Conditions should remain near seasonal as we approach the upcoming workweek. Temperatures are expected to remain near to slightly above seasonal norms.

AVIATION

(06Z TAFS) Issued at 303 AM AST Tue Mar 24 2026

Mainly VFR conditions expected across all terminals, with brief MVFR possible in SHRA. NE winds will persist through 24/16Z, then veer E at 1015 kt with occasional higher gusts near SHRA. VCSH/SHRA expected across windward terminals from 24/12Z to 24/19Z, then increasing along the Cordillera Central, affecting TJPS, TJSJ, and TJBQ through 24/23Z. SHRA with isolated VCTS may result in lower CIGs and brief VIS reductions. Low-level clouds will mainly range from FL020FL050, with deeper convective tops reaching FL060FL080.

MARINE

Issued at 303 AM AST Tue Mar 24 2026

A high pressure ridge will attempt to build between a lingering shear line over the region and another frontal system exiting the U.S. eastern seaboard today. This pattern will support light to moderate northeasterly winds today and tomorrow. By Thursday, the local pressure gradient will tighten as the high strengthens, promoting moderate to locally fresh easterly winds and choppy seas across the regional waters.

BEACH FORECAST

Issued at 303 AM AST Tue Mar 24 2026

A moderate risk of rip currents is expected across north and east facing beaches of Puerto Rico and the U.S. Virgin Islands through midweek. By Thursday or Friday, increasing winds will promote a broader expansion of the rip current risk to most local beaches, with this elevated risk persisting through much of the forecast period. Conditions are expected to further deteriorate early next week as a long-period northerly swell arrives, likely resulting in a high risk of rip currents by around Tuesday.

For more information and specific rip current details, please visit: https://www.weather.gov/beach/sju

SJU WATCHES/WARNINGS/ADVISORIES

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