textproduct: San Juan

KEY MESSAGES

Issued at 204 PM AST Wed Jun 24 2026

* A tropical wave will continue to move south of the region today. The moisture field could reach the islands later today, enhancing the potential for showers today as well as for afternoon showers and t-storms mainly across interior to W-NW PR. * High concentrations of Saharan Dust are expected to reach the U.S. Virgin Islands this afternoon, and Puerto Rico later this evening. This will result in hazy skies, reduced visibility and deteriorated air quality.

* Breezy to locally windy ESE winds will result in up to a moderate risk of rip currents across most coastal areas today as well as in choppy seas and Small Craft Exercise Caution conditions.

* An upper-level low will induce a surface trough that is forecast to cross the region on Saturday, promoting lighter winds as well as a limited flooding and lightning risk.

Short Term(This evening through Friday)

Issued at 204 PM AST Wed Jun 24 2026

Tranquil weather conditions prevailed today across Puerto Rico and the U.S. Virgin Islands under mostly clear to partly cloudy skies. By early afternoon, streamer activity downwind of El Yunque moved over portions of the San Juan metro area, leaving a few isolated to scattered showers with minimal accumulations. By mid-afternoon, additional showers began to develop across central and western Puerto Rico, causing no significant impacts, while the U.S. Virgin Islands observed mainly fair weather throughout the day. Maximum temperatures reached the upper 80s to low 90s across the lower elevations and the low to mid-80s in the higher mountains. Notably, the temperature at the Luis Munoz Marin International Airport in San Juan hit 90F by noon. Winds blew mainly from the east at 15 to 20 mph, with higher gusts and local sea breeze variations.

A tropical wave with its axis over the Lesser Antilles will continue to approach and move over the eastern Caribbean later today, slightly increasing moisture levels across the local islands. Precipitable water (PWAT) values are expected to reach 1.50 to 1.60 inches later today into early Thursday; however, the bulk of the moisture, with values up to 2.0 inches, is expected to remain over the Caribbean Sea, well south of the area. Nonetheless, this slight increase in moisture, combined with daytime heating and local effects, will drive a few more showers across central and western Puerto Rico this afternoon, bringing minor localized flooding impacts. Similar conditions are expected on Thursday, particularly during the afternoon hours.

Following the passage of the wave, a drier airmass will begin to filter into the region alongside high concentrations of Saharan dust, starting tonight and persisting through the weekend. This pattern will inhibit shower development, leading to predominantly dry conditions for the short-term forecast as PWAT values drop to between 1.20 and 1.30 inches. Due to the incoming Saharan dust, sensitive groups, particularly individuals with respiratory conditions, should take the necessary precautions to limit outdoor exposure and follow medical guidance.

Above-average seasonal temperatures will also persist through the weekend, with maximum temperatures ranging from the upper 80s to low 90s along coastal and urban areas, and from the upper 70s to low 80s in the higher elevations. Temperatures are forecast to increase further and become even warmer by early next week. Residents and visitors are strongly urged to practice heat safety by staying hydrated, avoiding strenuous outdoor activities during peak heating hours, and never leaving children or pets unattended in vehicles.

Long Term(Saturday through next Tuesday)

Issued at 328 AM AST Wed Jun 24 2026

At the beginning of the long-term period, an upper-level low will induce a surface trough that is expected to cross the region on Saturday. This feature will cause the surface high pressure over the central Atlantic to weaken, reducing the local pressure gradient and resulting in lighter winds that will gradually back to the northeast. Moisture content will increase to near-normal levels, with precipitable water values ranging from 1.60 to 1.75 inches, and locally higher amounts possible. In addition, Saharan dust concentrations will decrease as the dust plume moves away from the area, leading to improved air quality conditions. As a result, passing showers are expected across windward areas and the vicinity of the USVI during the early morning hours, followed by showers and isolated thunderstorms over the western sectors of Puerto Rico during the afternoon due to the combination of local effects and daytime heating. Temperatures at 500 mb are expected to remain above normal, around -5 C to -6 degrees C, but may still be sufficient to support a few lightning strikes.

On Sunday, drier conditions, with below-normal precipitable water values, and low concentrations of Saharan dust will begin to arrive, accompanied by a southeast wind flow. The primary hazard on this day will be warm to hot conditions, as indicated by forecast guidance showing 925 mb temperatures around two standard deviations above normal. Daytime highs are expected to reach the upper 80s to low 90s, and heat indices may exceed 100 degrees F, particularly across coastal and urban areas. An elevated heat risk will likely persist.

Early next week through mid-week, current guidance suggests that a tropical wave may approach the Caribbean Basin and increase low- level moisture across the local islands. Precipitable water values are forecast to increase to near-normal or slightly above-normal levels based on climatological data. This would likely enhance rainfall chances, leading to a greater frequency of showers and afternoon convection. At the same time, cooler temperatures aloft associated with lower 500 mb temperatures may provide additional support for convective development. However, Saharan dust is also expected to be present, and its interaction with the incoming moisture remains uncertain. Continue to monitor the forecast as updates become available.

AVIATION

(18Z TAFS) Issued at 204 PM AST Wed Jun 24 2026

VFR conds are forecast across all TAF sites. An approaching tropical wave may result in SHRA/TSRA that could lead to VCSH/VCTS at TJSJ/TJBQ thru 24/23Z. HZ is forecast after the wave passage beginning at TIST and TISX aft 24/22Z - 24/23Z and continuing through the weekend. Winds will remain from the E at 15 to 20 knots, with higher gusts and sea breeze variations thru 24/23Z, becoming light and VRB thru 25/13Z.

MARINE

Issued at 204 PM AST Wed Jun 24 2026

A broad high pressure system over the central Atlantic will maintain moderate to fresh easterly winds across the regional waters through Friday. These conditions will result in choppy seas across the regional waters and Caribbean passages, small craft must exercise caution. Winds will weaken and become gentle to moderate from the northeast by Friday night, as a surface trough moves north of the region. Shower activity associated with the trough may increase across local Atlantic Waters on Saturday. As the trough migrates westward, the pressure gradient will increase and winds will strengthen, becoming moderate to locally fresh from the southeast. Moderate to high concentrations of Saharan dust will gradually filter into the region tonight, bringing hazy skies, reduced visibility, and deteriorated air quality.

BEACH FORECAST

Issued at 204 PM AST Wed Jun 24 2026

The beach forecast remains on track, as the moderate risk of rip currents continues across most beaches of Puerto Rico and the U.S. Virgin Islands, with breaking waves between 2 and 4 feet. As mentioned in previous discussions, beachgoers must exercise caution, as life-threatening rip currents remain possible along the surf zone. The moderate risk will continue through Friday, though it may become low as a surface trough approaches the region and winds weaken. Nevertheless, beachgoers should take into account that life- threatening rip currents may develop near groins, jetties, reefs, and piers. By Sunday, as winds strengthen, the risk should gradually become moderate. Besides rip currents, residents and visitors are encouraged to stay weather alert due to showers and isolated thunderstorms that may develop in the afternoons and move near coastal areas of western/northwestern Puerto Rico, particularly over the weekend. Additionally, a dense plume of Saharan Dust will move across the local area, resulting in hazy skies, reduced visibility, and poor air quality. Individuals sensitive to these particles must follow medical recommendations.

SJU WATCHES/WARNINGS/ADVISORIES

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