Marine Weather and Tide Forecast for Carolina, PR

SHORT TERM
Today through Monday...

Upper-level cloudiness persisted over the islands today. Streamers developed downwind of the USVI and eastern PR by noon today, leaving measurable rainfall amounts over eastern PR. Maximum temperatures were from the mid-to upper-80s in general across all the islands.
However, across the southern coast of PR temperatures were from the upper 80s to low 90s. The wind was from the east to northeast between 15 and 20 mph with sea breeze variations and higher gusts across coastal areas.

A broad surface high pressure north of the region will remain in place for most of the short-term period, this will continue to promote moderate to fresh trade winds across the region. A developing upper-level low just north of the region will promote instability, with colder 500 mb temperatures around -8C, which will aid in thunderstorm development. The overall moisture content is expected to increase, with the low inducing a weak trade wind perturbation or surface trough on Sunday. Therefore, we expect an increase in shower coverage over the islands in general, particularly by Sunday evening into Monday.

A weak Saharan Air Layer will bring minor to moderate concentrations of Saharan dust from Sunday through early next week. This will promote hazy skies, but the concentrations will not be enough to suppress convective activity over the islands each day. Winds will acquire a southeasterly component on Sunday and Monday, and daytime temperatures will increase a few degrees compared to previous days, particularly across most coastal and urban areas of the islands.


LONG TERM
Tuesday through Saturday...

/From Prev Discussion issued at 503 AM AST Sat Jun 14 2025/

The long-term forecast begins wet and unstable, as a retrograding TUTT dominates the upper-level dynamics through at least the end of the workweek. Model guidance suggests cold air advection at mid- levels as the TUTT meanders over the region, with the median quartile of the combined ECMWF and GFS ensembles indicating 500 mb temperatures dropping to between -8C and -9C by Tuesday. These conditions will lead to steep low- to mid-level lapse rates, along with below-normal 250 mb height fields, which are favorable for deep convective activity.

These favorable dynamics will coincide with above-normal columnar moisture across the region. This pattern could lead to near-severe thunderstorms, particularly when combined with diurnal heating and orographic lifting. Potential impacts include frequent lightning, gusty winds, and small hail, especially at higher elevations in Puerto Rico during the afternoon hours. A primary limiting factor will be the presence of suspended Saharan dust, which could slightly reduce relative humidity around the 700 mb layer. While this may limit the areal coverage of showers and thunderstorms, localized strong activity remains likely. Additionally, the Saharan dust may enhance lightning activity within thunderstorms.

By Saturday, even though the TUTT moves farther northward, marginal instability will remain in place. At low levels, another tropical wave will maintain above-normal moisture over the northeastern Caribbean on Saturday. As a result, a limited to elevated flooding threat is expected each day, particularly over the interior and western portions of Puerto Rico during the afternoon hours. The most active day is expected to be Tuesday, as it coincides with the most favorable positioning of the TUTT over the region.

Aside from the likelihood of shower and thunderstorm activity, the presence of above-normal moisture combined with near to slightly above-normal temperatures could result in heat index values reaching levels associated with a limited to localized elevated heat threat, particularly across urban and coastal areas of the islands. This risk may increase toward the end of the workweek, as cloud cover decreases over the area. Residents are advised to stay hydrated, avoid prolonged outdoor activities during peak heating hours, and check on vulnerable individuals such as the elderly and young children.



AVIATION

(18Z TAFS)

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. However, SHRA expected to increase in general across the area terminals aft 15/16z. The 14/12z TJSJ sounding indicated ENE winds up to 21 kt blo FL050. Lighter winds are expected overnight due to land breeze variations.



MARINE

The surface high pressure north of the region will gradually shift east in the coming days. This will result in some fluctuations in the wind pattern over the region. But overall, expect moderate to locally fresh east to east southeast winds across the northeastern Caribbean through mid-week of next week, leading to choppy seas. A tropical wave south of the local islands will continue to move westward today, followed by another wave expected to approach the region by mid-week of the upcoming workweek. In the meantime, increasing moisture and instability associated with an upper-level trough will likely result in a rise in thunderstorm activity late this weekend into early next week.



BEACH FORECAST

Moderate rip current risks will persist along many north-, east-, and south-facing beaches over the coming days due to ongoing breezy conditions. This is especially true for locations exposed to open waters. While western beaches tend to be more protected, caution is still advised near jetties, piers, and channels where stronger currents can still develop.

Scattered showers or isolated thunderstorms may develop through the weekend, particularly over western Puerto Rico. Visitors should remain weather-aware, as any storm could bring dangerous lightning.
An increase in upper-level moisture and atmospheric instability may support more widespread thunderstorm activity by late weekend into early next week.

Beachgoers are reminded to swim near lifeguards whenever possible, steer clear of strong surf, and stay updated on evolving weather conditions.



FIRE WEATHER

Latest observations across southern PR indicated RH's between 48%-52% and gusty winds around 25 mph. A Fire Danger Statement continues in effect through late this afternoon for the southern coastal plains and hills of Puerto Rico. While dry and breezy conditions will persist through today, a gradual increase in moisture is expected to begin on Sunday, which may begin to ease fire weather concerns in the coming days.



SJU WATCHES/WARNINGS/ADVISORIES
PR...None.
VI...None.
AM...None.