textproduct: San Juan

KEY MESSAGES

Issued at 248 AM AST Fri Sep 25 2026

- Showers and thunderstorms will continue this afternoon across the interior and northwestern Puerto Rico. Therefore, there is a limited to elevated flooding risk across these areas today.

- A Heat Advisory is in effect from 10 AM to 3 PM AST for all of Puerto Rico, including Vieques, Culebra and the U.S. Virgin Islands.

- Warm temperatures are expected this weekend across Puerto Rico and the U.S. Virgin Islands. Heat-sensitive individuals should avoid outdoor activities and stay hydrated.

- Moisture will gradually decrease over the weekend, limiting showers and thunderstorms to localized portions of the islands.

- A moderate risk of rip currents is expected to continue along northern and eastern beaches of Puerto Rico and northern U.S. Virgin Islands through at least Saturday, increasing to high by Sunday into early next week.

Short Term(Today through Sunday)

Issued at 248 AM AST Fri Sep 25 2026

Overall quiet conditions prevailed across the islands, with only a few passing showers moving across the regional waters overnight. Minimum temperatures stayed in the mid-70s to low 80s along coastal and urban areas, while dropping into the mid to upper 60s in the mountains.

Variable weather conditions are anticipated across the region as we remain under the influence of a tropical upper-tropospheric trough (TUTT) lingering nearby over the next few days. At the surface, a high-pressure system will maintain light to moderate east- southeasterly winds through much of the period, shifting to easterly by Sunday. Precipitable water (PWAT) values will gradually decrease today to near or slightly below normal levels of 1.55 to 1.70 inches. This will favor mostly fair weather during the morning, with few passing showers across the U.S. Virgin Islands and eastern Puerto Rico. Afternoon convection is expected to follow across the interior and northwestern Puerto Rico. Because winds will remain light, any developing showers or thunderstorms could spread toward north-central and western portions of the island. As a result, the flooding risk remains limited to elevated across north-central to northwestern Puerto Rico, where urban and small-stream flooding is possible, especially in areas with soils already saturated from recent rainfall.

Similar conditions will persist through Saturday. By Sunday, however, PWAT values will increase to seasonal values with the arrival of a tropical wave. The combination of enhanced instability from the TUTT, cooler 500 mb temperatures (-8 to -9C), and moisture from the tropical wave will set the stage for an active afternoon, bringing showers and thunderstorms across interior and western Puerto Rico, as well as showers over eastern Puerto Rico.

In addition, an elevated heat threat continues today for Puerto Rico and the U.S. Virgin Islands due to abundant moisture, above-normal temperatures and east-southeast winds. Model guidance suggests 925 mb temperatures will gradually increase through Sunday, prolonging warm and humid conditions. As a result, a Heat Advisory is in effect for Puerto Rico and the U.S. Virgin Islands from 10 AM to 5 PM today. Residents and visitors are urged to stay hydrated, avoid strenuous outdoor activities during peak heat hours, take frequent breaks in shaded or air-conditioned environments, wear light- colored, and never leave children or pets unattended in vehicles.

Long Term(Monday through Friday)

Issued at 248 AM AST Fri Sep 25 2026

No major changes to the long term forecast. A tropical upper- tropospheric trough (TUTT) will continue to linger in the vicinity of the CWA. While it will shift from the northeast to southeast of the islands by late week, the position will remain unfavorable for the development of showers and thunderstorm over the forecast region as it will favor upper-level convergence. The low is expected to move away from the forecast area by late next week. Over the eastern Atlantic Ocean a low-level high pressure system will promote an ENE wind flow with a shift to ESE flow by the end of the week. The conditions are expected to become breezy to locally windy across the US Virgin Islands and Puerto Rico from Monday into late-week. The potential shift in wind direction may aid in the development of streamers from the US Virgin Islands, Culebra, Vieques, and El Yunque rainforest. While a tropical wave is expected to reach the forecast region between Monday and Tuesday the bulk of the moisture field associated with the system will remain to the south of the US Virgin Islands and Puerto Rico with lower than average precipitable water (PWAT) values intruding the region. Nonetheless, on Monday the atmospheric column is expected to be moister which may be favorable for the development of convective activity. Dry conditions in the low-to-upper levels is expected to persist into the week.

Conditions for the remainder of the forecast period are thus expected to be driven by local effects, particularly favoring afternoon showers and thunderstorms over the northwest and interior of Puerto Rico and some passing morning showers over the US Virgin Islands and eastern Puerto Rico. Mid-tropospheric temperatures are also forecasted to be below-to-around average for the season, increasing the potential for the development of deep convective cells. Risks associated to extreme heat continue to be one of the main concerns throughout the rest of the forecast period with 925 mb temperatures expected to be 2 standard deviations above normal ranges for the season into early next week showing a decreasing trend into mid week. Citizens ands visitors are invited to stay alert of the evolving weather conditions as we move into the weekend.

AVIATION

(06Z TAFS) Issued at 248 AM AST Fri Sep 25 2026

Mainly VFR conds are expected across all terminals during the forecast period. Aftn SHRA/TSRA development could result in VCTS at TJBQ/TJPS btw 25/17-23Z. Brief periods of MVFR/IFR with mtn obscurations are possible across central and western PR, particularly at TJBQ aft 25/17Z. Winds LGT/VRB to calm thru 25/14Z, becoming E-SE 10-15 kt with higher gusts and sea breeze variations thru 25/23Z, then becoming LGT/VRB overnight.

MARINE

Issued at 248 AM AST Fri Sep 25 2026

Light to moderate east to southeast winds will prevail through Saturday, generally at 10 to 15 knots or less, with seas mostly between 2 and 4 feet. A weak northerly swell will continue to spread across the Atlantic waters and passages, gradually increasing seas through the weekend. Marine conditions are expected to deteriorate from Sunday into early next week as the northerly swell becomes more pronounced and easterly winds strengthen, with seas building to around 5 to 6 feet and occasionally up to 8 feet across portions of the offshore Atlantic waters by Monday. Small Craft Advisory conditions may become possible across the Atlantic waters and local passages early next week. Scattered showers will remain possible at times, with isolated thunderstorms capable of producing locally higher winds and seas, frequent lightning, and brief reductions in visibility.

BEACH FORECAST

Issued at 248 AM AST Fri Sep 25 2026

A moderate risk of rip currents will continue today along the northern and northeastern beaches of Puerto Rico and Culebra, while a low risk prevails elsewhere. The moderate risk will expand into portions of northwestern and western Puerto Rico and the northern U.S. Virgin Islands on Saturday. Surf conditions are expected to become increasingly hazardous Sunday into early next week as a northerly swell reaches the local Atlantic waters, with breaking waves generally increasing to 5 to 7 feet along the northern and western beaches of Puerto Rico. This swell may result in a high risk of rip currents along the most exposed beaches during this period.

Other beach hazards will include heat through the weekend, especially during the late morning and afternoon hours. Afternoon showers and isolated thunderstorms will also remain possible each day, particularly along the western beaches of Puerto Rico, where lightning, brief heavy rainfall, and locally gusty winds may occur. If thunder is heard, leave the beach and water immediately and seek safe shelter.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory from 10 AM this morning to 3 PM AST this afternoon for PRZ001>013.

VI...Heat Advisory from 10 AM this morning to 3 PM AST this afternoon for VIZ001-002.

AM...None.