textproduct: San Juan

KEY MESSAGES

Issued at 227 PM AST Fri Jun 19 2026

* Seasonal to warmer conditions are likely this Fathers Day weekend and early next week, with heat indices ranging from the mid 90s and mid-100s across urban and low-lying areas of Puerto Rico and the U.S. Virgin Islands.

* Moderate to high concentrations of Saharan dust will spread across Puerto Rico and the U.S. Virgin Islands through this holiday weekend and early next week, with mainly hazy skies that will reduce visibility and deteriorate air quality. Sensitive groups must follow medical recommendations.

* Shower and thunderstorm activity expected to increase on Fathers Day, resulting in ponding of water over roadways and urban and small stream flooding over portions of the U.S. Virgin Islands and Puerto Rico.

Short Term(This evening through Sunday)

Issued at 227 PM AST Fri Jun 19 2026

Hazy skies prevailed across the islands throughout the day, while isolated thunderstorms were observed early this morning just south of St. Croix. As of 2 PM AST, highs were generally in the low 90s across most coastal areas. The wind was from the east around 15 to 20 mph with sea breeze variations and stronger gusts. Locally induced afternoon showers and isolated thunderstorms were developing from Utuado towards Rincon. This activity should end around sunset. Overall breezy conditions will prevail through the weekend, particularly across coastal areas.

Through early Saturday, a dense plume of Saharan dust will remain embedded across Puerto Rico and the U.S. Virgin Islands. This will maintain distinctly hazy skies, reduced visibilities, and poor air quality. Strong mid-level capping and a dry air mass will suppress deep organized convection, restricting shower development to isolated, diurnally induced afternoon activity over western Puerto Rico. Also, the combination of intense solar heating and persistent low-level moisture will drive elevated heat indices across coastal and urban areas, maintaining a risk for heat- related illnesses.

By Sunday, the forecast becomes more nuanced as an approaching tropical wave encounters a secondary pulse of moderate dust concentrations. This persistent Saharan Air Layer (SAL) event and its associated mid-level dry air will contend with the incoming tropical wave moisture, restricting shower coverage in general, as was the case with previous tropical waves that passed mainly to our south and that were surrounded by SAL. While precipitable water values are still forecast to increase to around 1.60-1.80 inches, the convective activity will likely be more fragmented and scattered than previously anticipated due to the dust entrainment. Hazy conditions will persist well into Sunday afternoon, with the main weather impacts transitioning to a mix of hazy sunshine and scattered showers or isolated thunderstorms over western PR. The primary hazards on Sunday will be ponding of water on roads and poor drainage areas across the U.S. Virgin Islands and eastern Puerto Rico, and minor urban/small-stream flooding over western PR during the late afternoon and evening hours.

Long Term(Monday through next Thursday)

Issued at 247 AM AST Fri Jun 19 2026

Model guidance continues to indicate a gradual improvement in weather conditions by Monday and persisting through midweek as a drier air mass filters into the region. Precipitable water values are forecast to decrease from near normal values (1.8 inches) on Monday to below-normal levels by Tuesday and Wednesday. Surface and mid-level relative humidity values are also expected to trend downward, resulting in a more stable atmospheric profile. With these stable conditions, we anticipate warm weather with temperatures along the coastal areas in the upper 80s to low 90s and in the 70s to low 80s across the higher terrains and rural areas. Residents and visitors should continue to practice heat safety, including staying hydrated and limiting prolonged outdoor activities during the hottest part of the afternoon, particularly across coastal and urban areas where heat indices may approach uncomfortable levels.

Although some passing trade-wind showers will remain possible across windward areas through the period, overall shower coverage and intensity should gradually diminish from Monday into Wednesday. While brief periods of wet roads may occur, especially across windward locations, significant rainfall impacts are not expected. As moisture decreases and atmospheric stability improves, a return to a more typical trade-wind weather pattern is anticipated through midweek, supporting generally favorable conditions for outdoor activities.

By Thursday, model guidance suggests a gradual increase in moisture across the area, leading to an uptick in shower activity. However, widespread rainfall is not currently anticipated, and conditions should remain generally favorable. Nevertheless, the increase in moisture may result in more frequent showers capable of producing localized ponding of water on roadways and minor flooding in poor- drainage and low-lying areas. Residents should monitor the latest forecasts and remain alert for changing weather conditions, especially if living in or traveling through flood-prone locations.

AVIATION

(18Z TAFS) Issued at 227 PM AST Fri Jun 19 2026

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours across all terminals. However, -TSRA over western PR should cause mostly VCTS at TJBQ thru 19/22z. Low- level winds will continue E-ESE at 12-20 kt with sea breeze variations and stronger gusts thru 19/22z. HZ due to Saharan dust continue across the region with VSBY near 6 SM.

MARINE

Issued at 227 PM AST Fri Jun 19 2026

A broad surface high pressure building over the Central Atlantic will continue to promote moderate to locally fresh east to east- southeast winds over the next several days, resulting in choppy seas across local waters and Caribbean passages; small craft should exercise caution. A dense layer of Saharan Dust will continue to filter into the region through the holiday weekend, resulting in hazy skies, reduced visibility, and poor air quality. A tropical wave is expected to approach the local area by Sunday morning, with showers and isolated thunderstorms likely to move across regional waters.

BEACH FORECAST

Issued at 227 PM AST Fri Jun 19 2026

No major changes to the beach forecast. The moderate risk of rip currents continues across the northern and eastern exposed beaches of Puerto Rico, including Vieques and Culebra, and St. Croix in the U.S. Virgin Islands, with a low risk elsewhere. Beachgoers must exercise caution, as life-threatening rip currents are possible along the beaches under the moderate risk. This holiday weekend, the threat will gradually spread across the islands as winds continue to strengthen, with most beaches of the islands under moderate risk. Besides rip currents, residents and visitors are encouraged to follow the latest weather forecast, as afternoon showers and isolated thunderstorms can be expected this holiday weekend and early next week, particularly near coastal areas of western/northwestern Puerto Rico. Beachgoers must exercise caution, as gusty winds can be expected and lightning cannot be ruled out. Moderate to high concentrations of Saharan Dust will continue to filter into the region through the holiday weekend and persist early next week, resulting in hazy skies, reduced visibility, and poor air quality. Beachgoers sensitive to these particles should follow medical recommendations.

FIRE WEATHER

Issued at 227 PM AST Fri Jun 19 2026

Critical fire weather conditions will remain a primary concern through the rest of this afternoon across the coastal plains and hills of southern Puerto Rico and St. Croix. A Red Flag Warning remains in effect until 4:00 PM AST due to the combination of critically dry fine fuels, sustained winds of 15 to 25 mph with gusts up to 30 mph, and minimum relative humidity values in the low 50s. These conditions will favor rapid wildfire ignition and extreme fire behavior, meaning any fires that develop will likely spread quickly and become difficult to contain. Outdoor burning is highly discouraged.

Looking ahead to tomorrow (Saturday), the elevated-to-critical fire weather threat is expected to persist, with little to no relief. The ongoing inflow of a dense Saharan Air Layer (SAL) will maintain an exceptionally dry mid-level air mass, capping deep vertical moisture and enhancing intense daytime heating across the region. As a result, afternoon relative humidity values are once again forecast to drop near 50% or lower across the southern slopes of Puerto Rico and St. Croix. When combined with sustained easterly trade winds remaining around 15 to 20 mph and further drying of already critical fuels, an enhanced fire danger will remain a primary concern on Saturday. Additional fire weather products may be required tomorrow morning if conditions align as expected.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 6 PM AST this evening for PRZ001>005-007-008- 010>013.

Red Flag Warning until 4 PM AST this afternoon for PRZ014-015- 018-025-027.

VI...Heat Advisory until 6 PM AST this evening for VIZ001-002.

Red Flag Warning until 4 PM AST this afternoon for VIZ002.

AM...None.