Marine Weather and Tide Forecast for Guánica, PR

.Short Term(This evening through Thursday)...
Issued at 218 PM AST Tue Aug 4 2026

Moderate concentrations of Saharan dust resulted in hazy skies across the islands this morning, while only a few passing showers moved across the local waters. Dust concentrations diminished significantly through the morning hours, allowing for improved visibility and a more favorable environment for convective development. At the same time, a larger portion of the urban and coastal areas experienced elevated heat risk compared to previous days as temperatures rose quickly, aided by above-normal moisture.

By late morning into the early afternoon, showers and isolated thunderstorms developed as a weak surface perturbation moved across the area from the northeast, inducing a more east-northeasterly low- level flow. This activity will continue through the remainder of the afternoon, mainly across the interior and southern to southwestern portions of Puerto Rico, while streamers downwind of the local islands persist. Some thunderstorms may become strong, producing frequent lightning, locally heavy rainfall, gusty winds, and small hail. A Special Weather Statement was issued earlier for portions of Ponce and Juana Diaz after Doppler radar indicated strong wind signatures and the potential for pea-sized hail. Although locally heavy rainfall will provide beneficial moisture across drought- affected areas, amounts will remain localized and insufficient to significantly improve ongoing drought conditions.

For Wednesday and Thursday, winds will remain from the east- southeast while a drier and more stable air mass gradually filters into the region. Precipitable water values will decrease to near or below seasonal normals, accompanied by drier mid-level air and warming aloft, limiting the coverage and intensity of afternoon convection. Still, local effects and daytime heating will support isolated to scattered afternoon showers across the interior and western to northwestern sections of Puerto Rico each day.

The main concern through the remainder of the forecast period will be the increasing heat risk. Above-normal low-level temperatures, decreasing cloud cover, and limited rainfall will promote dangerous heat across the urban and coastal areas of Puerto Rico and the U.S.
Virgin Islands. Heat Advisories will likely be needed on both Wednesday and Thursday, and if current trends continue, an Extreme Heat Warning cannot be ruled out across coastal and urban locations.

.Long Term(Friday through next Monday)...
Issued at 329 AM AST Tue Aug 4 2026

The long-term forecast remains on track, with variable weather conditions dominating the overall outlook. Surface high pressure extending across the western and central Atlantic will promote an easterly wind flow on Friday, and is expected to shift out of the southeast from Saturday onward as the high pressure migrates eastward. Upper-level low pressure moving across the region from Saturday into Monday will provide instability aloft, reflected in cooler 500 mb temperatures dropping to between -6°C and -7°C, particularly Saturday through Sunday.

Generally drier conditions are expected overall, though patches of low-level moisture carried by the trade winds will move across the region from time to time. The next tropical wave will pass from Saturday afternoon into Sunday morning, slightly increasing moisture content across the local islands. The latest model guidance continues to suggest precipitable water (PWAT) values of 1.75 to 2.00 inches on Saturday. However, because this wave is embedded in drier air and Saharan dust, it will move through relatively quickly, and PWAT values will drop rapidly by Sunday morning to below-normal levels around 1.25 inches. Consequently, overall rainfall with this wave will not be significant, though a few passing showers are likely over windward sections of the islands. During the afternoon hours, available moisture combined with diurnal heating and local sea-breeze effects could trigger localized convective activity across central and western Puerto Rico. Warmer-than-normal temperatures will persist throughout the forecast period. Model guidance indicates 925 mb temperatures near two standard deviations for this time of the year, which combined with lingering moisture could result in Heat Advisories or Extreme Heat Warnings, particularly over the weekend.

AVIATION
(18Z TAFS)
Issued at 218 PM AST Tue Aug 4 2026

Mainly VFR expected brief MVFR/IFR psbl in +SHRA/TSRA ovr interior and SW PR thru 04/22Z. VCTS at TJPS, with TEMPO TSRA producing brief reductions in CIGs /VIS, mtn obsc, and sfc gusts/vrb winds. VCSH expected at TJSJ/TIST/TISX. ENE sfc winds 12-18 kt with gusts up to 25 kt and sea breeze variations thru the aftn, bcmg lgt/vrb aft 04/23Z. Isold SHRA ovr lcl waters may affect ern terminals ovrnght, but VFR conds should prevail. ESE winds 10-15 kt with sea breeze variations aft 05/13Z. Isold to sct SHRA/TSRA dvlpg aft 05/16Z ovr the interior and W-NW PR may briefly affect TJPS/TJBQ with brief MVFR conds.

MARINE
Issued at 218 PM AST Tue Aug 4 2026

A surface high pressure building over the western Atlantic will maintain easterly moderate winds tonight and early Wednesday, becoming moderate to locally fresh on Wednesday afternoon as the local pressure gradient increases. As winds strengthen, building seas up to 6 feet may lead to choppy seas, particularly across local offshore Atlantic waters and Caribbean Passages. Isolated afternoon thunderstorms may generate locally hazardous marine conditions, mainly across the coastal waters of western Puerto Rico. Another tropical wave is forecast to approach and move across the local waters during the upcoming weekend.

BEACH FORECAST
Issued at 218 PM AST Tue Aug 4 2026

No changes were introduced to the beach forecast. The latest nearshore buoys reported seas between 1 and 2 feet, with the Ponce buoy reaching 3 feet, which should lead to breaking waves between 2 and 3 feet. Hence, the risk of rip currents remains low for the rest of today and is likely to persist tomorrow, Wednesday. Although the risk is low, beachgoers should be aware of life-threatening rip currents in the vicinity of jetties, reefs, piers, and groins. As winds gradually strengthen Wednesday onward, the risk of rip currents should become moderate, particularly across northern and eastern-facing beaches of Puerto Rico and the U.S. Virgin Islands.
At this point, life-threatening rip currents are possible along the surf zone; beachgoers must exercise caution. The moderate risk will likely prevail for the rest of the forecast period. Aside from rip currents, beachgoers should stay weather alert, particularly this afternoon and Wednesday, due to showers and isolated thunderstorms moving near coastal areas of Puerto Rico, with gusty winds and lightning.

FIRE WEATHER
Issued at 218 PM AST Tue Aug 4 2026

As mentioned in the previous discussions, critically fuels continue across the islands, particularly across the southern portions of Puerto Rico and St. Croix in the U.S. Virgin Islands. In the morning hours, stations across southern Puerto Rico reported winds between 10 and 13 mph, with gusty winds up to 20 mph. Additionally, relative humidity gradually decreased across the area (down to 60%), though it remained above fire weather criteria. As Saharan dust concentrations continue to diminish, the trade wind perturbation combined with daytime and local effects resulted in showers and isolated thunderstorms across the mountain ranges into southern portions of Puerto Rico, lowering the risk for fire weather for the rest of today. However, a more stable weather pattern and strengthening winds are likely in the next few days, and combined with very dry fuels, the fire danger will likely increase.
Residents and visitors are encouraged to continue to monitor the fire weather conditions and avoid outdoor burning.

SJU WATCHES/WARNINGS/ADVISORIES
PR...Heat Advisory until 4 PM AST this afternoon for PRZ001>005-007- 008-010>013.

VI...Heat Advisory until 4 PM AST this afternoon for VIZ001-002.

AM...None.