textproduct: San Juan

KEY MESSAGES

Issued at 431 AM AST Fri Dec 5 2025

* Limited shower activity is forecast for today, with mostly clear skies in the morning and afternoon.

* Seasonal daytime temperatures will persist over the islands today into the weekend, with temperatures in the upper 80s along the coastal areas and even in the low 90s across southern coastal areas.

* Stable weather conditions are forecast for the weekend into the upcoming workweek, with some passing showers but no flood threat across the islands.

* There is a moderate risk of rip currents across all northern coastal areas, including St. Thomas and St. Croix.

Short Term(Today through Sunday)

Issued at 431 AM AST Fri Dec 5 2025

Today through Sunday...

Conditions across Puerto Rico and the U.S. Virgin Islands remained tranquil, characterized by mostly clear to partly cloudy skies. Satellite and radar observations showed a few passing showers moving over the local Atlantic and Caribbean waters; however, some of these showers moved over the windward portions of the islands, resulting in minimal accumulations. Overnight temperatures were observed in the low to mid 60s along the higher elevations of Puerto Rico, while they remained in the low to mid 70s along the lower elevations.

Today, a mid-to upper-level ridge extending from the west will promote the intrusion of drier air and stable conditions aloft. This ridge is projected to be the predominant synoptic feature for the upcoming days, thus maintaining fair weather conditions across the islands with very limited rainfall. Despite these conditions, locally induced afternoon showers cannot be ruled out over central and western Puerto Rico each day. By late Saturday into Sunday, a surface high pressure system will begin to build north of the area, supporting drier conditions into early next week. However, patches of low-level moisture will move into the area on Sunday, promoting the development of a few showers across the region. Seasonal temperatures will prevail across the region during the weekend, ranging from the mid to upper 80s along the lower elevations of the islands and from the upper 70s to low 80s along the central mountain range of Puerto Rico. Overnight lows are expected to settle between the low to mid 60s in the higher elevations and the low to mid 70s in the lower elevations, ideal conditions for holiday festivities and the traditional "parrandas" this weekend.

Long Term(Monday through Friday)

Issued at 431 AM AST Fri Dec 5 2025

The long-term forecast remains on track under a favorable stable weather column across the islands. A strong and stalled mid to upper-level ridge expanding in the central Atlantic will be the main weather feature during the period.These features will hold a stable weather pattern with warmer conditions aloft and a strong trade wind cap inversion that limits vertical development across the islands. Under this pattern, and as suggested by the 500 MB temperatures in the -5 degrees, thunderstorm activity is not anticipated. Although a lightning threat is not forecasted, diurnal heating can still induce short-lived thunderstorms. Although very stable conditions will prevail, a strong surface high pressure over the Central Atlantic will drag patches of trapped moisture at 850 MB. According to the global model guidance, patches of trapped moisture with precipitable water values from 1.4 to 1.6 inches, close to the climatological normals, will move in and out of the region embedded in the trade winds. Therefore, in the afternoon, brief passing showers are possible due to diurnal heating and local effects. Surface winds will remain mostly from the east as the surface high pressure remains in the Central Atlantic, and veering winds are forecast from Monday onwards as the surface high pressure builds further into the Central and Eastern Atlantic.

By midweek, as the surface high pressure establishes across the central Atlantic, a tight in the pressure gradient will result in breezy conditions. Additionally, since the surface winds will remain east-southeasterly and plenty of sunshine will be present due to the lack of instability, daytime temperatures will remain just slightly above seasonal levels across the islands. According to the global model guidance, 925 MB temperatures suggest warmer conditions from Monday onwards, with Tuesday the warmest day of the long term.

AVIATION

(06Z TAFS) Issued at 431 AM AST Fri Dec 5 2025

VFR conds expected across all terminals during the fcst period. Mainly fair weather conds expected today; however, few passing showers moving across portions of Puerto Rico and the USVI will result in VCSH across all TAFs sites thru 05/14Z. Winds will remain from the ENE at less than 10 kt thru 05/13-14Z, increasing between 12 to 16 kt thru 05/22-23Z, with higher gusts and sea breeze variations.

MARINE

Issued at 431 AM AST Fri Dec 5 2025

Today, an extending surface high pressure will dominate the islands, producing moderate easterly winds and seas reaching up to 5 feet. A drier air mass is also moving across the region, which will limit shower activity throughout the day. Global model guidance indicates that energy from an incoming northerly swell will reach the northern offshore Atlantic waters, likely leading to higher seas and hazardous marine conditions. An increase in surface winds will result in wind-driven seas, and energy from a north-northwesterly swell will increase seas across the Atlantic waters and the local passages.

BEACH FORECAST

Issued at 431 AM AST Fri Dec 5 2025

There is a low to moderate risk of rip currents across the northern and northeastern coastal areas of Puerto Rico, Culebra, St. Thomas, and St. Croix. Global model guidance indicates that energy from an incoming northerly swell will reach the northern offshore Atlantic waters, likely leading to higher seas and hazardous marine conditions. An increase in surface winds will result in wind-driven seas, and energy from a north-northwesterly swell will increase seas across the Atlantic waters, the local passages, and the locally exposed beaches across the islands, including the U.S. Virgin Islands.

SJU WATCHES/WARNINGS/ADVISORIES

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