textproduct: San Juan

KEY MESSAGES

Issued at 247 AM AST Sun Nov 1 2026

* Passing showers will move in across the islands this morning, followed by stronger showers and thunderstorms for the interior and west of Puerto Rico.

* Warmer than normal heat indices will persist through the workweek, so stay hydrated and take plenty of breaks when outdoors.

* A moderate rip current risk will persist through the workweek for the north facing beaches of Puerto Rico and Culebra.

Short Term(Today through Tuesday)

Issued at 247 AM AST Sun Nov 1 2026

A few thunderstorms moved through the local waters through the night hours, but rainfall over land was very limited. Skies were mostly cloudy, and temperatures dropped to the mid 70s to low 80s in coastal areas, and in the mid 60s across the Cordillera Central.

For today, high pressure will continue to drive the trade winds from the east-southeast, but winds will be a little stronger, around 13 kts. Under this flow, drier air will be advected today. However, there is enough moisture to generate afternoon showers and thunderstorms across the interior and western Puerto Rico. Rainfall accumulations should be less than what was experienced yesterday. A similar pattern is expected on Monday, with a drier air mass filtering from 850 to 500 mb. The winds will be a little stronger as well. Low level moisture should carry passing showers into the region.

By Tuesday, conditions are expected to change. First, the wind flow will become mostly from the south, from the surface into the mid levels of the atmosphere. This will cause temperatures to soar, with even higher heat indices anticipated. Also, the probability of precipitation will increase, mostly after the evening hours, as significant moisture is lifted from the Caribbean.

Long Term(Wednesday through Sunday)

Issued at 247 AM AST Sun Nov 1 2026

A generally warm and humid weather pattern is expected across Puerto Rico during the long term period. Precipitable water (PWAT) values are expected to remain generally elevated most of the forecast period, ranging between 1.9 and 2.3 inches. Low-level relative humidity (850 to 700 mb) is expected to remain generally between 70% and 85%, while mid-level moisture (700 to 500 mb) will increase considerably from Wednesday through Friday, reaching values near or above the 75th climatological percentile of the month of November. Some drying is then anticipated toward the end of the period, particularly on Sunday, as drier air filters into the region. Meanwhile, 500 mb temperatures around -5 to -6C will contribute to some atmospheric instability, particularly during periods of stronger daytime heating. At the synoptic level, an upper-level low, along with its associated surface low and frontal boundary, will move northward across the Atlantic waters during the period. This evolution will favor southerly low-level winds, allowing tropical moisture to be transported toward the region, particularly on Saturday as the system moves farther north. Light winds will generally prevail across the local area, contributing to weak steering flow and potentially slow moving showers.

A warm and humid air mass will remain in place on Wednesday, with elevated moisture supporting widespread shower development, particularly across the interior and western portions of the island. Combined with daytime heating, sea breeze convergence, and orographic lifting, periods of heavy rainfall are possible. Light winds will result in weak steering flow, allowing showers to move slowly and increasing rainfall accumulations, with localized urban and small stream flooding possible. Wednesday is currently expected to be one of the wettest days of the period.

Somewhat drier air is forecast to filter into the mid and upper levels on Thursday and Friday, resulting in a slight decrease in available moisture and shower activity. Nevertheless, light winds, daytime heating, and local effects will continue to support afternoon showers, particularly across interior and western Puerto Rico. The overall flooding threat should decrease slightly during these days, although isolated heavy rainfall cannot be ruled out. Moisture is expected to increase again on Saturday as southerly to southwesterly winds transport additional tropical moisture into the region pulled by the low and frontal boundary moving across the Atlantic, north of Puerto Rico and USVI. This could make Saturday another one of the wettest days of the long term period, favoring shower and thunderstorm development. Light winds will still contribute to weak steering flow and potentially slow moving showers. Consequently, locally heavy rainfall could lead to increased accumulations and localized flooding.

By Sunday, drier air is expected to reach the region, favoring a decrease in available moisture and overall shower activity. Although isolated to scattered afternoon showers may still develop across the interior and western sections due to daytime heating and local effects, rainfall coverage and intensity should generally decrease. Continue to monitor the forecast as confidence increases and updated model guidance becomes available.

AVIATION

(06Z TAFS) Issued at 247 AM AST Sun Nov 1 2026

Mainly VFR conditions expected this morning. SCT SHRA and TSRA expected across the local waters, occasionally reaching the terminals. After 17Z, organized convection is expected for the Cordillera Central. Periods of reduces VIS and low ceilings are expected for TJPS and TJBQ. Winds will be from the ESE at 12-14 kts, with stronger gusts.

MARINE

Issued at 247 AM AST Sun Nov 1 2026

A frontal boundary over the western Atlantic will remain north of the local waters and gradually weaken through early next week. The associated surface pressure pattern will support a generally easterly wind flow across the regional waters. Passing showers and isolated thunderstorms are possible, with locally higher winds and seas near thunderstorms. The wind and wave guidance suggests that seas may increase somewhat early next week as east to east-southeast winds strengthen Monday and Tuesday. Mariners should monitor the latest coastal waters forecast for updates on winds and seas.

BEACH FORECAST

Issued at 247 AM AST Sun Nov 1 2026

A moderate risk of rip currents is expected across many north and east facing beaches of Puerto Rico and the U.S. Virgin Islands through much of the forecast period. Beachgoers should exercise caution and check the latest beach forecast before entering the water. Isolated thunderstorms may also affect beaches, particularly during the afternoon. If you hear thunder, leave the beach and seek shelter in a substantial building or enclosed vehicle.

SJU WATCHES/WARNINGS/ADVISORIES

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