textproduct: San Juan

KEY MESSAGES

Issued at 207 PM AST Wed Oct 28 2026

* Showers and thunderstorms will continue to affect the north central to north western municipalities of Puerto Rico. Additional rounds of showers could affect the southern portions of the islands.

* Expect showers to affect the US Virgin Islands at times through tomorrow morning.

* Exceptionally high tides will continue for the next couple of days, with localized flooding across vulnerable areas anticipated, mostly across northern Puerto Rico.

* High Rip Current Risk will continue today for northern Puerto Rico and Culebra, while a moderate risk continue for Vieques and for the Virgin Islands.

Short Term(This evening through Friday)

Issued at 207 PM AST Wed Oct 28 2026

Active weather over the Caribbean waters south of Hispaniola persisted farther east than anticipated this morning, as the drier air mass expected to move over the region only reached the eastern half of the CWA, where reduced shower activity prevailed. Meanwhile, several rounds of heavy showers and isolated thunderstorms developed over the southwestern Caribbean waters, with some showers affecting southern and southwestern Puerto Rico, mainly from Cabo Rojo to Ponce. However, the latest radar observations indicate that convective activity has diminished considerably, with most of the remaining showers confined to the offshore Caribbean waters. Although a few locations across north-central Puerto Rico briefly reached Heat Advisory criteria, these conditions were highly localized. In fact, several weather stations across the CWA reported temperatures 1 to 3 degrees cooler than 24 hours ago during the early morning hours, likely due to the presence of high cloud cover. Therefore, a Heat Advisory was not issued. Nevertheless, heat index values may still exceed 100 degrees across coastal and urban areas, although overall heat impacts should be lower than in previous days.

For the remainder of today, the region will remain between an upper- level trough over the western Caribbean and a ridge extending across the eastern Caribbean. Although ridging aloft and relatively dry mid- level conditions may limit convective development, available moisture, daytime heating, and local sea breeze convergence may still support additional afternoon showers and isolated thunderstorms, particularly across interior and northwestern Puerto Rico. However, lingering cloud coverage and the recent decrease in convective activity introduce some uncertainty regarding afternoon development. Any stronger thunderstorms could produce locally heavy rainfall and ponding of water on roads and in poorly drained areas.

For Thursday and Friday, the GFS and ECMWF suggest a gradual increase in mid-level moisture as the influence of the ridge aloft weakens. Although precipitable water values are expected to remain near seasonal levels, generally between 1.5 and 1.8 inches, both models indicate increasing moisture in the 700-500 mb layer, along with cooler 500 mb temperatures and steeper mid-level lapse rates. However, fluctuations in low- to mid-level moisture and relatively weak 850-700 mb lapse rates may continue to limit shower and thunderstorm coverage at times. Therefore, afternoon convection will remain highly dependent on daytime heating, sea breeze convergence, and local effects. While somewhat lower rainfall accumulations remain possible on Thursday, the improving mid-level environment may favor stronger convection by Friday, with locally heavy rainfall, frequent lightning, and urban and small stream flooding possible where the heaviest activity develops.

Long Term(Saturday through next Tuesday)

Issued at 207 PM AST Wed Oct 28 2026

Moist and unstable conditions are forecast to start the long term period. Moisture will continue moving over the local area, maintaining PWAT values above 2 inches for most of the period. A surface high over the Atlantic will result in an easterly flow to start the period, before becoming more southeasterly to start the next week and continue throughout the period. Mid-level drier air is forecast to persist Saturday, before becoming less pronounced Sunday onwards. An upper trough will be mainly west of the region to start the period, however some uncertainty persists with model guidance now suggesting that the upper trough will move away from the region early next week. However, guidance shows low- to mid-level moisture increasing as the period continues. The trough will support through at least the weekend, cool mid-level temperatures (-6 to -7 C), steep lapse rates, and upper-level divergence, factors that promote cloud development and support deeper convection over the region. 500 mb temperatures will warm up somewhat to around -6C during the workweek. Nocturnal and morning showers and t-storms are expected mainly over the weekend, especially across the U.S. Virgin Islands and eastern to southeastern Puerto Rico. With above normal moisture persisting, afternoon convection will focus primarily over interior, western, and northwestern Puerto Rico, with streamers also developing from El Yunque and the local islands. Heavy rainfall totals may trigger urban and small stream flooding. Additionally, t- storms may produce frequent lightning and gusty winds.

AVIATION

(18Z TAFS) Issued at 207 PM AST Wed Oct 28 2026

Mainly VFR conds expected across all terminals. SHRA/ISOLD TSRA across interior and NW PR thru 22Z may cause mtn obscurations and brief MVFR conds near TJBQ, although it will depend on cloud clearing above. Winds ESE-SE at 8-16 kts, bcmg lgt/VRB overnight. SE winds increasing aft 14Z Thu, with gusts up to the low 20s kts possible. VCTS expected at TJBQ/TJPS aft 17Z Thu, with brief MVFR/TSRA possible at TJBQ.

MARINE

Issued at 207 PM AST Wed Oct 28 2026

Recent observations from nearshore buoys indicate seas of 3 to 4 feet, while offshore Atlantic buoys show seas of 5 to 6 feet. Small craft operators should continue to exercise caution, particularly across exposed Atlantic waters and local passages. Expect subsiding seas, as the long-period northerly swell continues to diminish overnight. A surface high- pressure system over the central Atlantic will maintain moderate to locally fresh east to southeasterly winds across the regional waters over the next several days, resulting in choppy conditions at times, especially across offshore waters and exposed coastal areas. Meanwhile, scattered showers and isolated thunderstorms will continue to affect the Caribbean waters and local passages through the remainder of today, potentially producing brief periods of reduced visibility, locally gusty winds, and rougher seas.

BEACH FORECAST

Issued at 207 PM AST Wed Oct 28 2026

A gradually improvement in beach conditions is forecast from tomorrow onwards, as the long period northerly swell diminishes. Nevertheless, breaking waves between 5 and 7 feet across northern- exposed beaches of the islands could lead to life-threatening rip currents. Therefore, the high rip current risk continues for the beaches along western to northeast Puerto Rico through 6 PM today. Nevertheless, we encourage people to monitor our forecast, as we are planning to extend the High Rip Current Risk through tomorrow morning. Residents and visitors are encouraged to heed the advice of lifeguards, beach patrol flags and signs. Although the risk will become moderate over the next few days, beachgoers must still exercise caution as life- threatening rip currents are possible along the surf zone. Besides rip currents, extreme high tides will continue. This combined with the fading swell could lead to localized minor coastal flooding across vulnerable coastal areas.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk until 6 PM AST this evening for PRZ001-002- 005-008-010-012.

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