textproduct: San Juan

KEY MESSAGES

Issued at 135 PM AST Mon Jun 15 2026

* Generally stable and fair weather conditions will prevail through much of the week, although a slight increase in moisture and shower activity is possible toward the end of the week.

* Warm to hot conditions will persist, with elevated heat indices posing a risk to vulnerable populations and those spending extended periods outdoors.

* An elevated risk of rapid wildfire spread continues, particularly across southern and western Puerto Rico.

* The risk of rip currents will range from low to moderate over the coming days along many exposed beaches.

* Trace concentrations of Saharan dust will linger through midweek. A plume of moderate to high dust concentrations is expected to arrive around Thursday, resulting in hazy skies, reduced visibility, and deteriorating air quality.

Short Term(This evening through Wednesday)

Issued at 135 PM AST Mon Jun 15 2026

A dry and overall stable air mass will linger across the region through Tuesday, followed by a minor increase in low-level moisture by midweek. Model guidance indicates precipitable water (PWAT) values suppressed to near or below the 25th percentile, around 1.25 inches, before recovering slightly toward 1.60 inches by late Wednesday. This highly stable environment is supported by dry mid-levels, with 700-500 mb relative humidity dropping to 15-30% and 850-700 mb relative humidity remaining below 40%. Additionally, the latest NASA aerosol optical thickness model and real-time total precipitable water products confirm a dry profile, with a light layer of Saharan dust, keeping skies generally hazy and suppressing widespread deep convection.

Winds will remain brisk out of the east to east-southeast at 15 to 20 knots, with 925 mb wind speeds consistently remaining between 15- 20 knots, supporting mostly quick passing showers. High-res model guidance indicates minimal rainfall accumulations across the region. Diurnally driven showers will be brief and sparse, limited mostly to light passing showers across windward areas during the overnight/early morning hours, followed by isolated, shallow afternoon convective development over western Puerto Rico. However, by Wednesday, localized amounts of up to an inch of rain are possible in western PR as instability increases somewhat as an upper- level trough retrogrades across the Atlantic. Strong daytime heating will persist, with maximum temperatures in the upper 80s to low 90s across coastal and urban areas. Heat indices are expected to exceed 100F each day across the lower elevations of the islands.

Long Term(Thursday through Monday)

Issued at 300 AM AST Mon Jun 15 2026

Model guidance suggests a modest increase in moisture late this week as a tropical wave passes south of Puerto Rico and the U.S. Virgin Islands. At the same time, the persistent mid-level ridge is forecast to shift west of the region while a lingering upper- level trough east-northeast of the area exerts greater influence, resulting in slight cooling aloft and a gradual weakening of the trade wind cap. However, dry mid-level air is expected to persist, and moderate Saharan dust concentrations forecast through Friday should temper the overall coverage and intensity of showers and thunderstorms.

As a result, only a modest increase in shower activity and the potential for isolated thunderstorms is anticipated from Thursday into Friday. While localized heavier downpours cannot be ruled out, the prolonged dry pattern and significant rainfall deficits should keep the overall flooding threat limited. Beyond Friday, forecast uncertainty increases, but a generally typical trade-wind pattern with passing showers and isolated afternoon convection is expected to continue. Overall confidence in the long-term forecast remains moderate, as the timing and interaction of these features continue to vary among model guidance.

AVIATION

(18Z TAFS) Issued at 135 PM AST Mon Jun 15 2026

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. Low-level winds will prevail E-ESE at 15- 25 kt, bcmg light and variable at the sfc overnight. HZ due to Saharan dust will continue across the region, but VSBY will remain P6SM.

MARINE

Issued at 135 PM AST Mon Jun 15 2026

A broad area of high pressure over the central Atlantic will continue to support moderate to locally fresh trade winds across the region. Seas are expected to range between 4 and 6 feet, with occasional higher waves across the offshore waters and local passages, resulting in Small Craft Exercise Caution conditions. Winds are forecast to ease slightly from Tuesday into Wednesday, allowing seas to gradually subside to between 3 and 5 feet. By Thursday, a tropical wave is forecast to approach the northeastern Caribbean, bringing a modest increase in moisture and shower activity across the local waters. At the same time, Saharan dust concentrations are expected to increase to moderate to high levels, leading to hazy skies and the potential for reduced visibility.

BEACH FORECAST

Issued at 135 PM AST Mon Jun 15 2026

A moderate risk of rip currents will prevail tonight for most beaches across Puerto Rico, including Culebra and Vieques, as well as St. Croix in the U.S. Virgin Islands. From Tuesday through early Thursday, the rip current risk will vary between low and moderate levels. Beginning Thursday afternoon, increasing winds will cause a moderate risk to become reestablished along most beaches, with these conditions expected to persist through the weekend.

Beachgoers should remain vigilant, swim near lifeguards when possible, and follow the guidance of local authorities and beach warning flags, as rip currents can create life-threatening conditions. Additional information on location-specific rip current risks is available at weather.gov/beach/sju.

FIRE WEATHER

Issued at 135 PM AST Mon Jun 15 2026

A Fire Danger Statement (RFDSJU) remains in effect until 4 PM AST this afternoon. Surface observations have reported minimum relative humidity values primarily in the lower 50 percent range, along with wind gusts of 25 to 30 mph. Combined with above- critical Keetch-Byram Drought Index (KBDI) values and increasingly dry fuels, these conditions are contributing to elevated fire danger across the area. Similar, or even locally critical, fire weather conditions capable of supporting rapid wildfire growth and spread may persist over the next several days if the current weather pattern continues.

SJU WATCHES/WARNINGS/ADVISORIES

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