textproduct: San Juan

KEY MESSAGES

Issued at 314 AM AST Sun Aug 16 2026

- A passing tropical wave will continue to move across the region this morning, bringing few fast moving passing showers across portions of Puerto Rico and the U.S. Virgin Islands.

- A drier airmass is expected to follow the tropical wave along with low to moderate concentrations of Saharan dust.

- Breezy to windy conditions will continue through later tonight, secure loose objects as they could blow around.

- A Heat Advisory is in effect from 10 AM to 5 PM AST for urban and coastal areas of Puerto Rico and the U.S. Virgin Islands.

- Marine and coastal hazards are ongoing and will remain through this evening. For more detailed information, please refer to the Marine and Beach Forecast sections.

Short Term(Today through Tuesday)

Issued at 314 AM AST Sun Aug 16 2026

Relatively calm weather prevailed overnight under clear to partly cloudy skies. A passing tropical wave brought a few showers across northern and eastern Puerto Rico, as well as the surrounding Atlantic and Caribbean waters, with no significant impacts. It was another warm night, with minimum temperatures reaching the upper 70s to low 80s in coastal and urban areas of Puerto Rico and the U.S. Virgin Islands, and dropping to the low-to-mid 70s at higher elevations. Breezy easterly winds continued overnight at 10 to 15 mph, with higher gusts and land breeze variations.

The passing tropical wave is expected to move westward and away from the region this morning, followed by a drier airmass containing moderate concentrations of Saharan dust. As this dry air filters into the area, precipitable water values will drop well below normal climatological levels to 1.18-1.35 inches. Combined with stable conditions aloft and warm mid-level temperatures (at 500 mb) promoted by a mid-level ridge, shower activity will remain limited through at least midweek. Despite the overall dry conditions, daytime heating and local effects could still trigger localized afternoon convection, resulting in a few showers and isolated thunderstorms across interior and western Puerto Rico. Breezy to locally windy easterly winds will persist today before gradually diminishing on Monday as a surface high pressure system weakens.

An elevated heat threat remains across urban and coastal sections of Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands today as above-normal temperatures, elevated heat indices, and abundant sunshine continue to dominate the region. Consequently, a Heat Advisory is in effect from 10 AM to 5 PM AST. These conditions increase the risk of heat exhaustion, particularly for vulnerable populations and anyone working or active outdoors during peak heating hours; residents and visitors are strongly advised to stay hydrated, limit direct sun exposure, and take frequent breaks in shaded or air-conditioned spaces. Additionally, the combination of strong easterly winds, low humidity, and dry soils will favor rapid wildfire spread, prompting a Fire Danger Statement along Puerto Rico and the U.S. Virgin Islands.

Long Term(Wednesday through Sunday)

Issued at 314 AM AST Sun Aug 16 2026

Variable conditions are still expected in the long-term, with high uncertainty during the second part of the workweek. A surface high pressure building over the Western Atlantic should maintain winds mainly from the E-ENE (shifting briefly from the E-SE on Thursday) throughout most of the period, leading to breezy to locally windy conditions. The latest global solutions indicate a tropical wave (former AL94) approaching the Caribbean Basin and moving across the CWA late Wednesday night into Thursday. According to the deterministic guidance of the ECMWF and GFS, PWAT values may increase to 2.0 - 2.2 inches, with a low chance of reaching 2.2 - 2.4 inches. Additionally, members of the grand ensemble are trending toward wetter values during Thursday, with moisture content in the low and mid levels reaching above climatological normal (around 80%). Under that pattern, lines of strong showers and thunderstorms could move over windward sections of the islands throughout all day, with afternoon convection over interior and western/northwestern Puerto Rico. Rainfall accumulations could lead to ponding of water over roadways and poorly drained areas, along with minor flooding. Nevertheless, theres high uncertainty as the tropical wave encounters unfavorable conditions such as drier airmass, Saharan Dust, and strong wind shear. Although the NHC has ended , residents and visitors should continue to monitor this system. As the tropical wave moves out of the local area, a dry slot, along with concentrations of Saharan Dust, should filter into the region, with PWAT values dropping to below normal (1.2 - 1.4 inches). Although daytime heating and local effects may enhance afternoon convection, showers and isolated thunderstorms could move over western Puerto Rico, though rainfall accumulations will remain limited. By Saturday, a perturbation in the trades, along with an upper-level low, may increase moisture content across the CWA, with PWAT values reaching typical values for this time of the year (between 1.6 and 1.8 inches). This may introduce some instability and enhance convection across the area once again, as the frequency of showers and thunderstorms may increase over windward sections.

AVIATION

(06Z TAFS) Issued at 314 AM AST Sun Aug 16 2026

Mainly VFR conds expected across all TAF sites. Breezy to windy conditions will prevail today, with E winds between 16-22 kt and gusts up to 30 kt through 16/23Z. Fast moving SHRA could result in VCSH across PR & USVI terminals today as a passing tropical wave departs the region. HZ from Saharan dust will continue affecting the local islands, resulting in VIS reductions through 16/23Z.

MARINE

Issued at 314 AM AST Sun Aug 16 2026

A tight pressure gradient will maintain fresh to locally strong easterly winds and choppy to rough seas around 5 to 7 feet, with occasional seas of 8 to 9 feet across the offshore waters and local passages today. Therefore, Small Craft Advisories remain in effect through at least this evening. Showers and thunderstorms associated to a departing tropical wave should diminish this morning across the Caribbean waters and Mona Passage.

BEACH FORECAST

Issued at 314 AM AST Sun Aug 16 2026

A high risk of rip currents will continue today across the east, north, and southern beaches of Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands due to wind-driven short period waves. Therefore, a Rip Current Statement remains in effect through at least tonight for all the islands. Beachgoers are urged to stay out of the water and heed the advice of lifeguards, beach patrol flags, and posted signs. From Monday onward, a low to moderate risk of rip currents is expected as winds decrease and seas subside through midweek. However, remember that even when the risk is low, life- threatening rip currents can occur near groins, jetties, reefs, and piers.

FIRE WEATHER

Issued at 314 AM AST Sun Aug 16 2026

Critical fuel conditions continue to persist across the islands, with extreme drought conditions across portions of the southern coastal plains and eastern portions of Puerto Rico. A tropical wave with its axis located over Puerto Rico, will continue to move westward and away from the region later today. However, a drier airmass will follow and it is expected to drop relative humidity significantly to below threshold values. As anticipated, these conditions combined with little to no wetting rainfall, ongoing rainfall deficits, stressed vegetation, and dry fuels will maintain conditions favorable for rapid fire spread. The greatest concern remains across southern and southwestern Puerto Rico, where fuels are particularly dry and recent fire activity has been more frequent. However, elevated fire danger will continue across Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands. Therefore, a Fire Danger Statement is in effect from 10 AM through 5 PM AST. Residents and visitors are encouraged to avoid outdoor burning, as conditions will likely be favorable for wildfire ignition and rapid spread.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late tonight for PRZ001>003-005- 007-008-011>013.

Heat Advisory from 10 AM this morning to 5 PM AST this afternoon for PRZ001>005-007-008-010>013.

VI...High Rip Current Risk through late tonight for VIZ001-002.

Heat Advisory from 10 AM this morning to 5 PM AST this afternoon for VIZ001-002.

AM...Small Craft Advisory until midnight AST tonight for AMZ711-733- 735-741.

Small Craft Advisory until noon AST today for AMZ712-716-723-726.