textproduct: San Juan

KEY MESSAGES

Issued at 331 AM AST Sat Nov 7 2026

- Slow-moving afternoon showers will elevate the threat for urban and small-stream flooding, localized flash flooding and mudslides across portions of the interior to northeastern PR through Sunday.

- Showery conditions expected to continue over the U.S. Virgin Islands today, where minor urban flooding is possible.

- There is a high risk of life threatening rip currents across the north-facing beaches of Puerto Rico through the weekend with a peak on Sunday.

- By mid-week next week a stable weather pattern is expected to prevail across the region.

Short Term(Today through Monday)

Issued at 331 AM AST Sat Nov 7 2026

A weak synoptic pressure gradient will dominate the northeastern Caribbean through the short-term period as a broad surface low tracks across the western to central Atlantic well north of the region. Aloft, mid-to-upper level ridging south of the region combined with weak troughing to the northeast will maintain light west-southwesterly flow and low vertical wind shear. In this nearly stationary environment, low-level steering winds will generally range from 5 to 10 knots. Meanwhile, recent satellite imagery and regional moisture analyses show a pronounced plume of deep tropical moisture surrounding Puerto Rico and the U.S. Virgin Islands. Forecast soundings show precipitable water content peaking between 2.00 and 2.25 inches through early Sunday, exceeding the 75th percentile of climatology. This high moisture profile, coupled with 850-700 mb relative humidity around 80 percent and high 850 mb equivalent potential temperatures, will provide an unstable, saturated column highly favorable for convective development.

Given the weak steering flow, convective development through Sunday will be governed predominantly by diurnal heating, local sea breezes, and orographic lift. High-res guidance and regional precipitation forecasts highlight showers and thunderstorms expanding across the interior, north, and east of PR during the afternoon hours, while scattered showers cross the USVI and regional waters, with a higher probability of heavy showers in and around St. Croix. Ensemble rainfall guidance indicates 24-hour accumulations ranging from 1 to 1.50 inches over north-central and eastern Puerto Rico, with localized swaths exceeding 2 inches where persistent or training convection materializes. Because of the slow storm motion, rainfall duration over some areas will be prolonged. Therefore, the primary weather hazards will be localized urban and small-stream flooding, rapid rises along small rivers, ponding of water in poorly drained urban areas, and isolated mudslides along steep terrain.

A transition toward a drier air mass will take place on Monday as the deepest moisture axis shifts eastward and mid-level dry air filters into the region. Relative humidity in the 700-500 mb layer is expected to fall near 50 percent, while precipitable water values decrease back toward seasonal normals between 1.60 and 1.80 inches. Shower activity across the USVI will become more isolated, while afternoon showers and thunderstorms across PR become more localized, concentrating mainly over the interior and eastern municipalities where sea breeze convergence focuses.

Long Term(Tuesday through Saturday)

Issued at 331 AM AST Sat Nov 7 2026

As the low pressure north of the region moves further into the central Atlantic and the surface high pressure builds to the NW of the region, winds should become more S-SSE across the Islands throughout the long-term period. Calm winds will prevail into mid- week with conditions becoming locally breezy by Friday. The beginning of the week will be characterized by variable conditions as with average precipitable water (PWAT) and abundant moisture in the low and mid levels. Low steering winds combined with local effects, daytime heating, and sea breeze convergence will lead to rainfall activity with a focus on the interior and northern portions of Puerto Rico each afternoon. Shower activity from streamers and advective showers will should also move during the morning and over night hours across the US Virgin Islands, SE Puerto Rico and the San Juan metro area each day as well. During the second part of the next workweek, a mid-level ridge will move into the vicinity of the region to the east of the islands, warming the mid-temperatures, leading to sinking air, and stability aloft. This will act as a limiting factor for the development of deep convective cells by the end of the workweek. Another limiting factor for the development of widespread convection will be the lack of available moisture in the mid-levels.

Thus, the potential for excessive rainfall and lighting associated risks will decrease as the week progresses. The focus of the activity will be predominantly the interior and northern portions of Puerto Rico during the afternoons. This level of risk may lead to ponding of water over roadways and poorly drained areas, without ruling out isolated urban flooding. The available moisture, above average low tropospheric temperatures, and low surface winds will lead to a level of heat that may affect those individuals 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.

AVIATION

(06Z TAFS) Issued at 331 AM AST Sat Nov 7 2026

VFR early in the fcst period, with -RA possible at TISX and mostly VCSH across all terminals. However, by noon, sct convection expected to develop over the eastern interior of PR and in and around the U.S. Virgin Islands. This may cause tempo MVFR conds at TJSJ/TISX/TIST thru 07/23z. Mostly VCTS at TJPS thru this period. Winds will prevail from the west to southwest btw 5 and 15 kt, with the highest wind speeds across the USVI terminals. A weak WNW sea breeze is expected at TJSJ.

MARINE

Issued at 331 AM AST Sat Nov 7 2026

Light to locally moderate west to southwesterly winds will dominate the northeastern Caribbean through the weekend as a broad surface low tracks across the western to central Atlantic, well north of the region. A long period northeasterly swell from this low will continue to spread across the Atlantic waters through early Monday, with most of the swell energy expected from tonight into Sunday. This may result in building seas of around 5 to 6 feet across the Atlantic waters and passages. Shower and thunderstorm activity expected mainly across the eastern waters and the Anegada Passage. Gusty winds, reduced visibility, sudden waterspouts, and frequent lightning are possible with this activity. Light trade winds return early in the workweek.

BEACH FORECAST

Issued at 331 AM AST Sat Nov 7 2026

A long-period (~11 seconds) northeasterly swell will continue to gradually spread across the Atlantic waters, resulting in a high risk of rip currents through the weekend, mainly affecting the north- facing beaches of Puerto Rico and Culebra. From this afternoon through Sunday, building seas will increase the likelihood of life-threatening rip currents. As a result, a Rip Current Statement is in effect from today through at least Sunday. Across the U.S. Virgin Islands, a moderate risk of rip currents is expected, while a low risk will prevail along the southern beaches of Puerto Rico. Caution is always recommended as life- threatening rip currents remain possible is the surf zones. Additionally, isolated thunderstorms and showers may affect beachgoers, especially during the afternoons. If you hear thunder, seek shelter immediately.

SJU WATCHES/WARNINGS/ADVISORIES

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

VI...None.e SSW to WSW at 5 to 15 knots, accompanied by local sea breeze variations and higher gusts. AM...None.