Marine Weather and Tide Forecast for Carolina, PR

SHORT TERM
Rest of today through Thursday...

Mostly sunny skies prevailed through the morning hours across the islands. Isolated showers were developing early in the afternoon hours over portions of the northwestern quadrant of PR, and downwind of the USVI and eastern PR. Isolated thunderstorms are still expected to develop mainly over northwest PR this afternoon.
Maximum temperatures were from the upper-80s to low-90s across the lower elevations of the islands with heat indices between 105-110F. Winds were from the southeast up to 15 mph.

A mid-to upper-level trough over the western Atlantic will gradually replace the ridge aloft and promote more unstable conditions, particularly on Thursday. Meanwhile, at the surface, an associated front and pre-frontal trough will increase moisture content and promote a deep southerly steering wind flow over the northeastern Caribbean. This will cause an increase in afternoon shower and thunderstorm activity over the north-central and eastern portions of PR, where the flood threat will be elevated on Wednesday afternoon, and increasing in coverage on Thursday. Also, an elevated heat threat with Heat Advisory conditions are likely once again on Wednesday across most coastal municipalities of PR and across the USVI.


LONG TERM
Friday through Tuesday...

/From prev discussion issued at 517 AM AST Tue Oct 14 2025/

No major changes were introduced to the long-term forecast. A wet and unstable weather pattern is expected for the upcoming weekend, which may improve for the first part of the workweek. Winds should remain light on Friday and Saturday, shifting from the southwest influenced by a surface high pressure system over the central Atlantic and a broad polar trough, which will pool the remnants of the frontal boundary and high tropical moisture. From the latest deterministic guidance of the GFS and the ECMWF, Precipitable Water (PWAT) values should remain seasonal to above climatological normal (2.0 - 2.2 inches). Additionally, the polar trough reflected in the mid to high levels may deepen enough to cool 500 mb temperatures (-6.5 to -7.5 degrees Celsius), increasing instability and supporting deep convection. The Galvez- Davison Index (GDI) also suggests the potential of isolated to scattered thunderstorms through at least Sunday. Hence, the frequency of showers and thunderstorms should remain high, affecting mostly windward sections during the night through early mornings, with deep convection activity remaining over the mountain ranges of Puerto Rico in the afternoons. Winds should increase and turn from the southwest as the surface high pressure migrates west and approaches the CWA Due to abundant moisture content over the area, afternoon convection should concentrate over northwestern Puerto Rico. Given the expected conditions, the lightning and flooding threat will remain limited to elevated during that period.

An improvement in weather conditions is expected by late Monday due a drier air mass filtering into the region. The latest model guidance shows a decrease in PWAT values (1.7 - 1.9 inches), although there’s high variability between ensemble members due to a tropical wave that global models suggest should move south of the CWA Nevertheless, the combination of daytime heating, local effects, and available moisture will enhance shower and thunderstorm activity, mainly over the western/northwestern portions of Puerto Rico; however, the flooding threat should remain limited.

The latest model guidance indicates that Sunday may be the warmest day of the long-term period, followed by a gradual decrease in 925 mb temperatures for the remainder of the period.
Nevertheless, heat indexes are still very likely to reach 100 degrees and may meet Heat Advisory Criteria. Hence, the heat threat will remain elevated for the long-term forecast.



AVIATION

(18Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. However, tempo MVFR conds are expected at TJBQ thru 14/22z due to SHRA/TSRA. Elsewhere, mostly VCSH expected. The 14/12z TJSJ sounding indicated ESE winds btw 4-21 kt fm the sfc to 4000ft.



MARINE

A broad surface high pressure north of the region will maintain moderate east to southeast trade winds today. Then, winds will become light to gentle from the south-southwest Wednesday onwards.
A frontal boundary approaching the region will induce a pre-frontal trough for the second half of the workweek, increasing shower and thunderstorm activity across the regional waters and passages.
Pulses of a long period northerly swell will reach the Atlantic waters and passages from Friday into early next week.



BEACH FORECAST

There is a moderate risk of rip currents along the north and eastern coast of Puerto Rico. Similar conditions are expected during the next few days. However, by late Friday into Sunday, pulses of a long period northerly swell will increase the threat of life-threatening rip currents along the north coast of Puerto Rico, and the US Virgin Islands.



SJU WATCHES/WARNINGS/ADVISORIES
PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007- 008-010>013.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

AM...None.