textproduct: San Juan

KEY MESSAGES

Issued at 300 AM AST Sat Nov 8 2025

* A tropical wave will bring more widespread showers and thunderstorms on Sunday, especially across eastern Puerto Rico, with an increased risk of urban and small-stream flooding. Breezy conditions are also expected.

* Life-threatening rip currents are likely across most shorelines through at least early next week.

* A seasonable weather pattern will prevail the upcoming workweek, with no significant weather threats anticipated at this time.

* Across the U.S. Virgin Islands, tropical wave moving across the eastern Caribbean tonight into Sunday will bring an increase in passing showers.

Short Term(Today through Monday)

Issued at 300 AM AST Sat Nov 8 2025

Overnight, most of the frequent rainfall activity was observed across the eastern and southern sections of Puerto Rico, where rainfall accumulations ranged from 0.10 to 0.50 inches. Therefore, over those areas, skies remained mostly cloudy, while partly cloudy to clear skies prevailed elsewhere, particularly across western Puerto Rico and the U.S. Virgin Islands. Temperatures ranged from the upper 70s to low 80s along the coastal areas and from the upper 60s to low 70s across the mountainous regions.

Today, typical local effects will dominate the weather pattern. Sea breeze convergence is expected to lead to the development of afternoon showers and a few isolated thunderstorms over western Puerto Rico. Elsewhere, especially across eastern Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands, occasional passing showers are possible during the night and early morning hours. Temperatures are expected to reach the mid- to upper 80s across coastal areas and the mid- to upper 70s across the higher terrain. Winds will gradually increase from today onward as a tropical wave approaches the region from the southeast.

As the weekend progresses, a tropical wave moving across the eastern Caribbean will bring a gradual increase in moisture. On Sunday, precipitable water values are expected to increase to above-normal levels for this time of year, reaching the 75th percentile. The latest model guidance suggests relative humidity at 500 mb will remain near to slightly above normal through this period, further supporting vertical development of convective activity. This will enhance the potential for more widespread showers and isolated thunderstorms across the area. The most active period is anticipated Sunday afternoon. Regardless, eastern Puerto Rico is forecast to experience the greatest rainfall activity. These showers will move quickly with the strengthening easterly winds, but some may produce heavy rainfall capable of causing urban and small stream flooding, particularly in low-lying or poor drainage areas.

By Monday, lingering moisture behind the departing tropical wave will maintain unstable weather conditions across the region. Scattered showers and isolated thunderstorms are expected through the day, particularly across western and interior Puerto Rico during the afternoon. While the overall intensity of rainfall is expected to be lower compared to Sunday, periods of moderate to locally heavy rain could still lead to ponding of water on roadways and minor flooding in isolated spots. Temperatures will remain near normal for this time of year, with highs in the mid-80s along the coast and cooler readings across higher terrain.

Long Term(Tuesday through Saturday)

Issued at 300 AM AST Sat Nov 8 2025

A mid- to upper-level ridge will dominate the local weather pattern throughout the forecast period, maintaining relatively stable conditions across the region. At the surface, a broad high- pressure system positioned northeast of the islands will yield an easterly wind flow. Meanwhile, a frontal boundary is forecast to stall north of the area toward the end of the cycle.

Under the subsidence associated with the ridge aloft, available moisture is forecast to erode from Tuesday onward. Precipitable water values are expected to decrease to below 1.75 inches, while 500 mb temperatures are anticipated to range between -4C and -5C. This combination will promote a more stable and drier air mass, limiting vertical development of showers and overall convective activity.

As a result, a seasonal weather pattern is anticipated across Puerto Rico and the U.S. Virgin Islands with passing showers affecting portions of eastern Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands during the nighttime and early morning hours, followed by limited afternoon convection over western and interior Puerto Rico, driven by local effects and diurnal heating. Additionally, seasonable temperatures are expected to prevail, with daytime highs reaching the mid-to-upper 80s in coastal areas and lower elevations.

No significant weather threats are anticipated at this time.

AVIATION

(06Z TAFS) Issued at 300 AM AST Sat Nov 8 2025

All TAF sites should experience VFR conditions. However, SHRA/TSRA may develop across W PR after 08/17Z, possibly affecting JBQ through about 08/22z. This may result in brief periods of MVFR conditions. ESE winds at 10-15 kts and higher gust near the heaviest rainfall activity and typical sea breeze variations to continue. Increase in VCSH over TISX, TIST, and TJSJ after 09/00Z as a tropical wave continues to approach the area.

MARINE

Issued at 300 AM AST Sat Nov 8 2025

A surface high pressure across the north-central Atlantic will yield moderate easterly winds across the local waters during the next several days. An increase in winds and shower activity is expected on Sunday as a tropical wave/easterly disturbance moves across the eastern Caribbean. Although the northerly swell will continue to subside, a smaller secondary northeasterly swell will continue to affect the local waters during the weekend.

BEACH FORECAST

Issued at 300 AM AST Sat Nov 8 2025

A moderate risk of rip currents will continue to prevail across most of the shorelines of Puerto Rico and the U.S. Virgin Islands through at least Monday. Therefore, life-threatening rip currents are likely in the surf zone, particularly near piers, jetties, and channels. Conditions are expected to improve by mid-week, next week.

SJU WATCHES/WARNINGS/ADVISORIES

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