textproduct: San Juan

KEY MESSAGES

Issued at 1255 AM AST Sun Aug 9 2026

- A Heat Advisory in effect from 10 AM through 5 PM for the lower elevations of Puerto Rico and the US Virgin Islands.

- High concentrations of Saharan Dust will persist through Monday. Sensitive groups must follow medical recommendations.

- Limited rainfall is expected for the next several days, allowing drought conditions to continue worsening across Puerto Rico and the U.S. Virgin Islands.

- Low fire weather conditions may persist today, as RH values increase due to the nearby tropical wave.

Short Term(Today through Tuesday)

Issued at 1255 AM AST Sun Aug 9 2026

Overnight, dry and stable conditions prevailed across Puerto Rico and the U.S. Virgin Islands. Moderate Saharan dust concentrations remained across the region and contributed to warm overnight conditions, with temperatures staying in the lower 80s along coastal areas and in the 70s across the mountains.

Today, a tropical wave will continue to move south of the islands, increasing low-level moisture through Monday. However, the highest concentrations of Saharan dust are expected today. The combination of dust, dry air aloft, and a persistent trade wind inversion will limit the significant shower development despite the nearby wave. Brief passing showers are possible across windward areas, followed by limited afternoon activity over western Puerto Rico. Hazy skies, reduced visibility, and poor air quality will remain the main impacts from the Saharan dust, particularly for people sensitive or with respiratory conditions.

Heat will be another concern today. Following the warm overnight temperatures, strong daytime heating could push afternoon highs into the mid 90s, particularly across coastal and urban areas. The combination of heat and humidity will result in hazardous heat indices. Therefore, a Heat Advisory is in effect from 10 AM through 5 PM. Those working or spending time outdoors should drink plenty of water, take frequent breaks in shaded or air conditioned locations, and reduce strenuous activity during the hottest part of the day.

On Monday, the tropical wave will move out of the region and Saharan dust will gradually decrease back to moderate. Some dry air aloft will remain, but sufficient moisture should be available for passing morning showers and localized afternoon activity, mainly across interior and western Puerto Rico. Periods of heavier showers could produce minor ponding of water on roads and in poor- drainage areas. This pattern will continue through Tuesday.

Long Term(Wednesday through Sunday)

Issued at 1255 AM AST Sun Aug 9 2026

Weather conditions during the long-term period will start off variable as a tropical wave moves over the islands and wind speeds continue to gradually increase. Precipitable water (PWAT) values will start off at generally normal values (up to around 2 inches) as the wave moves over the islands. The interaction between this wave and the atlantic surface high will result in a breezy to locally windy, E to ESE, steering flow. Along with diurnal heating, sea breeze convergence and local effects, this setup will help trigger afternoon convection across interior to W-NW PR, as well as lines of showers downwind of El Yunque and the local islands. Passing showers will also reach windward sectors. The heaviest showers could promote ponding of water and sustain a flooding risk. Low to moderate concentrations of Saharan Dust will also persist to start the long term period and continue through at least the workweek. Drier air will reach the islands on Thursday, limiting widespread shower activity, with breezy to locally windy flow also limiting accumulations. Increasing uncertainty develops Friday onward as the tropical waves that would affect the region Friday and during the next weekend are currently being monitored by the National Hurricane Center (NHC). The latest 2 AM Tropical Weather Outlook has these waves with a low and medium formation chance, respectively. Although the forecast has been based on the typical weather pattern under generally increasing moisture and breezy to windy easterly flow. Due to the extended forecast window, adjustments to the track and intensity of the moisture remain possible toward the end of the period. Please continue to monitor the latest Tropical Weather Outlooks (TWOs) issued by the NHC for more information regarding the formation chance of these tropical waves.

AVIATION

(06Z TAFS) Issued at 1255 AM AST Sun Aug 9 2026

VFR conditions across all TAF sites. High concentrations of HZ will prevail across all terminal from 09/12Z onwards. Visibilities should remain around 6 SM. Brief periods of MVFR condt possible due to VCTS near TJBQ and TJPS from 09/17Z through 09/23Z. Winds will remain from the E around 15 to 20 kts and occasional higher gusts.

MARINE

Issued at 1255 AM AST Sun Aug 9 2026

A combination of a surface high pressure over the central Atlantic and a tropical wave approaching the region will promote breezy conditions across the local waters, resulting in occasionally choppy seas of up to 6 feet. Therefore, small craft operators should exercise caution. The strongest showers and thunderstorms associated with the tropical wave are expected to prevail mainly across the Caribbean waters, resulting in locally hazardous marine conditions, including gusty winds, higher seas, and frequent lightning near thunderstorms. By midweek, another tropical wave is expected to move across the region, increasing the potential for showers and thunderstorms over the local waters. By Thursday, a tightening pressure gradient in response to a strengthening surface high over the central Atlantic will promote another increase in easterly winds. This will likely result in hazardous conditions for small craft, with winds of 15 to 20 knots, locally up to 25 knots, and seas potentially building to 5 to 7 feet.

BEACH FORECAST

Issued at 1255 AM AST Sun Aug 9 2026

A moderate risk of rip currents is expected to prevail throughout the forecast period, mainly along the north-facing beaches of Puerto Rico and the U.S. Virgin Islands. Breezy easterly winds associated with a surface high pressure over the central Atlantic and passing tropical waves will maintain choppy surf conditions, particularly along exposed northern and eastern beaches. The moderate rip current risk is expected to persist into midweek. By Thursday, a tightening pressure gradient associated with a strengthening surface high over the central Atlantic will result in stronger easterly winds and increasingly choppy surf. Therefore, some areas could experience a high risk of rip currents by the end of the period. Beachgoers should exercise caution, particularly along the northern coastline of Puerto Rico and the U.S. Virgin Islands, where life-threatening rip currents will remain possible.

FIRE WEATHER

Issued at 1255 AM AST Sun Aug 9 2026

The fire weather threat is expected to remain low today as moisture increases to around 50 and 60 percent across southern Puerto Rico due to the passages of a tropical wave located over the Caribbean waters. However, ongoing drought conditions, fires can still start and spread, especially with the increased winds around 15 to 20 mph at times. Residents and visitors should continue to avoid activities that could create sparks or flames near dry vegetation, and never leave an ignition source unattended.

We encourage everyone to continue to monitor the forecast for any changes in the fire weather threat throught the day.

SJU WATCHES/WARNINGS/ADVISORIES

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

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

AM...None.