textproduct: San Juan

KEY MESSAGES

Issued at 304 PM AST Mon Nov 9 2026

- Ongoing shower and thunderstorm activity is increasing the chance for urban and small-stream flooding and frequent lightning and gusty wind conditions across the interior and north central of Puerto Rico. Landslide and flash flooding cannot be ruled out due to saturated soils.

- Slow moving showers induced by the islands continue to affect portions of the US Virgin Islands, Vieques and Culebra.

- Northeasterly swells will maintain a high rip current risk for the north- facing beaches of Puerto Rico and the US. Virgin and Culebra through Tuesday afternoon.

- Conditions are expected to become more seasonal from mid-week onwards with afternoon shower activity focusing on the northern interior and northwestern Puerto Rico during the afternoons.

Short Term(This evening through Wednesday)

Issued at 304 PM AST Mon Nov 9 2026

The forecast remains predominantly on track. The CWA is positioned within a col region with calm SSE winds of less than 10 knots as a surface low-pressure system located to the NE of the US Virgin Islands moves further into the central Atlantic. This windflow continues to advect tropical moisture inland. Thus, the islands are currently embedded within a pool of tropical moisture with a relatively humid vertical profile and precipitable water (PWAT) values above average levels for the season (1.8-2.2 inches). The variable winds and available moisture will lead to showers and thunderstorms across northern interior, northwestern and northeastern Puerto Rico during the afternoon. As the conditions linger across the region, a similar pattern is expected Tuesday with the focus of the activity being across the northern interior of Puerto Rico. The US Virgin Islands will continue to see calmer conditions with scattered showers possible each day. Thus, flooding in urban areas, roads, small streams and washes along with low chance of isolated floods is an expected risk. Some regions within the CWA have reported around 4 inches of rain over the past 72 hours. Given that some of the soils may be either saturated or close to saturation landslides cannot be ruled out especially over areas that have received frequent downpours over the last few days. Additionally, some of these heavy showers are associated with strong thunderstorms that could also result in areas with frequent lightning and gusty wind conditions.

A more amenable period will begin on Wednesday, as an airmass with reduce moisture (PWAT below 1.8 inches) begins to move across the region. The wind will become more SE but will remain calm. Thus, any shower and thunderstorm activity that does develop will be primarily focused on the northern interior, and northwestern portions of Puerto Rico.

The available moisture, low surface winds, and 925 mb temperatures above 22 degrees Celsius, will lead to level of heat that may affect those individuals extremely sensitive to heat especially when outdoors without effective cooling and/or adequate hydration. Individuals are invited to continue monitoring the weather conditions as they evolve.

Long Term(Thursday through Monday)

Issued at 231 AM AST Mon Nov 9 2026

The long-term forecast remains on track, with weather conditions becoming more stable by late this weekend. A surface high pressure building over the Central Atlantic should increase local pressure gradient, with strengthening winds from the S-SE. The latest model guidance suggests abundant tropical moisture moving into the region early Thursday and Friday, with PWAT values up to 1.75 inches, typical for this time of the year. However, moisture content should gradually diminish as a drier air mass filters in the mid-levels on Saturday and Sunday, limiting deep convection. In the mid and upper levels, the nearby short-wave troughs should introduce troughiness across the area on Thursday and Friday, with slightly cool mid-level temperatures (around -6 C), allowing cloud growth. However, a building ridge northeast of the CWA should dominate the weather pattern in the weekend, warming mid-level temperatures (up to -4 and -5 C), leading to subsidence and stability aloft. Additionally, the Galvez-Davison Index suggest the potential for thunderstorms across the local area mainly on Thursday and Friday, while Saturday and Sunday should become more shallow in the afternoons. The latest model solutions suggest a frontal boundary approaching the northern Caribbean by Sunday, though the best area of deep convection should remain outside the CWA. Overall, showers are likely to move during the night and morning hours, particularly across windward sections of the islands, followed by afternoon convection, particularly across interior and northwestern/northern Puerto Rico. As mentioned above, the best opportunity for deeper convection is Thursday and Friday, with mainly ponding of water over roadways and poorly drained areas, along with isolated urban and small stream flooding.

Under a S-SE wind flow, the latest model guidance suggest warmer than normal 925 mb temperatures across the CWA. With the available moisture, heat indices could easily exceed 100 F, particularly across urban and low-lying areas of the islands during the peak hours of the day. Therefore, the heat threat will remain limited to elevated.

AVIATION

(18Z TAFS) Issued at 304 PM AST Mon Nov 9 2026

SHRA/TSRA will continue to develop across interior PR and near the USVI through approximately 09/23Z. Mtn obsc and frequent lightning are likely. Brief MVFR to IFR conditions are possible within this activity due to reduced VIS and low CIGs. Surface winds will range from 510 kt, primarily influenced by sea breezes with a weak ESE background flow. VFR conditions are expected to prevail after 09/23Z as convection diminishes. Another round of aft convection possible btwn 10/16-23z, ESE winds around 10kt with sea breeze aft 10/13z.

MARINE

Issued at 304 PM AST Mon Nov 9 2026

Energy from a NE swell will continue to maintain seas at 4-5 feet across the northern offshore waters today as a surface low-pressure system continues to move eastward across the Atlantic Ocean. With a building high pressure system over the west Atlantic, the islands are currently located in a col region with a light-to-gentle SSE breeze that will persist until Wednesday. A moderate-to-strong SSE breeze will prevail from Wednesday into Friday. Waves will range between 4-5 feet across northern offshore waters and between 2-5 along the southern offshore waters. Showers and isolated thunderstorms may produce locally higher winds and seas.

BEACH FORECAST

Issued at 304 PM AST Mon Nov 9 2026

A northeasterly swell will continue to impact the Atlantic waters and local passages, producing breaking waves of 5 to 7 feet along the north-facing beaches of Puerto Rico and Culebra. This means life- threatening rip currents are likely in the surf zones. Pulses from this swell are likely to continue until Tuesday afternoon.

As a result, a high risk of rip currents was extended through at least Tuesday afternoon along north-facing beaches of Puerto Rico, local passages and Culebra. Also, a moderate risk of rip currents persists along the north facing beaches of Vieques and the U.S. Virgin Islands. Beachgoers should remain cautious, as rip currents are possible. Continue to monitor the forecast for updates.

Thunderstorms pose another beach hazard, particularly during the afternoon hours. If thunder is heard, seek shelter immediately.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through Tuesday afternoon for PRZ001-002- 005-008-010-012.

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