textproduct: San Juan

KEY MESSAGES

Issued at 245 PM AST Thu Jul 9 2026

* Moderate to high concentrations of Saharan dust will peak today, with moderate concentrations persisting through the weekend.

* A Heat Advisory remains in effect through this afternoon. While warm conditions are expected to persist each day, another period of dangerous heat is possible early next week.

* Breezy to windy easterly winds will persist through the weekend before gradually returning to more typical conditions next week. As a result, hazardous marine conditions for small craft and a moderate risk of rip currents are present.

* Favorable conditions for fire spread will peak from Friday through the weekend. Avoid outdoor burning or activities that could produce sparks.

Short Term(This evening through Saturday)

Issued at 245 PM AST Thu Jul 9 2026

Windy and hazy conditions dominated across Puerto Rico through the morning as the pressure gradient remained tight over the northeastern Caribbean and a drier air mass continued to filter into the region behind the departing tropical wave. East to east- southeast winds produced frequent gusts between the upper 20s and lower 30s mph across exposed and coastal locations. These gusty conditions resulted in at least one report, with a tree falling in Cabo Rojo, bringing down utility power lines and blocking the roadway. Meanwhile, radar and satellite imagery have shown very limited convective development this afternoon, with only isolated shallow showers affecting portions of the Aguadilla vicinity. Elsewhere, abundant sunshine, increasing Saharan dust, and dry mid- level air have suppressed more widespread shower activity while promoting hot daytime temperatures.

For the remainder of the afternoon, no significant shower or thunderstorm development is anticipated. Increasing mid-level drying and subsidence, combined with the continued entrainment of Saharan dust, will continue to suppress convective development through sunset. Fair weather is therefore expected to prevail, aside from an isolated passing shower.

On Friday and Saturday, a drier and more stable air mass will become firmly established across the northeastern Caribbean as moderate to locally high concentrations of Saharan dust persist across the region. Model guidance continues to indicate precipitable water values between 1.3 and 1.4 inches, well below climatological normals, while relative humidity in the 700-500 mb layer remains within 20% to 30%, supporting stable atmospheric conditions. Although some shallow low-level moisture will continue to support isolated passing trade-wind showers overnight and during the morning hours, the dry air aloft will limit cloud depth, with little to no afternoon convective development anticipated.

Although 925-mb temperatures are forecast to ease slightly compared to today, above-normal daytime temperatures will persist through the period. Moderate to high concentrations of Saharan dust will continue to promote warm, hazy conditions, with localized areas of elevated heat stress remaining possible each afternoon, particularly across urban and coastal locations. Breezy easterly winds will persist as the Atlantic surface ridge remains the dominant weather feature, while the combination of low humidity, dry fuels, and gusty winds will continue to support an elevated fire danger through Saturday. Refer to the Fire Weather Discussion below for additional details.

Long Term(Sunday through Thursday)

Issued at 210 AM AST Thu Jul 9 2026

Theres more agreement in the global model solutions regarding early next weeks weather pattern. A series of surface high pressures will maintain E-ESE winds throughout the forecast period, with breezy to locally windy conditions across coastal areas of the islands. Moderate concentrations of Saharan Dust will likely linger on Sunday, limiting any shower activity, but will gradually diminish and remain low in the evening. As mentioned in the previous discussion, model guidance suggested the approach of a tropical wave into the Caribbean Basin, but they differed in the time of arrival. From the latest solution, both GFS and ECMWF suggest that moisture content will increase across the CWA by late night Sunday into Monday, with 850 - 700 mb values ranging between 50 and 70 %. In terms of instability, the proximity of an upper-level low northeast of the CWA may introduce slight instability across the area, as model guidance indicates cool mid-level temperatures (around -8 degrees Celsius) on Sunday and Monday. With the presence of low concentrations of Saharan Dust, thunderstorm development, if any, may be enhanced, increasing lightning potential. Hence, the highest chance of shower and thunderstorm activity can be expected on Monday, affecting mainly windward sections of the islands in the morning, followed by afternoon convection over interior and western Puerto Rico. Rainfall accumulations may lead to ponding of water over roadways and poorly drained areas, along with minor flooding. Based on the latest NASA GEOS-5 Dust AOT, Saharan Dust concentrations should increase from Tuesday onwards, resulting in hazy skies, reduced visibility, and poor air quality, with limited shower activity. Sensitive groups must follow medical recommendations.

Seasonal to near-above-normal temperatures are expected in the forecast period, and combined with available moisture, heat indices will likely exceed 100 degrees Fahrenheit mainly over urban and low- lying areas of the islands. As mentioned in previous discussions, the presence of Saharan Dust may inhibit nighttime cooling, with warmer minimum temperatures. Therefore, the heat threat will likely remain limited to elevated throughout the forecast period.

AVIATION

(18Z TAFS) Issued at 245 PM AST Thu Jul 9 2026

Mainly VFR conds will prevail across all terminals through the fcst period. Brief VCSH may affect TJBQ through around 09/22Z, but no sig operational impacts are expected. HZ associated with Saharan dust will continue across the local islands, with sfc vsby generally remaining 6SM or higher. E-ESE sfc winds at 15-25 kt with gusts up to 30 kt will continue through around 09/22Z, becoming lighter overnight.

MARINE

Issued at 245 PM AST Thu Jul 9 2026

A strong surface high pressure centered over the Atlantic will continue to support moderate to fresh easterly winds, occasionally strong, across the regional waters through at least late Friday. These conditions will maintain choppy to hazardous seas, with wave heights generally ranging from 6 to 7 feet over the offshore Atlantic waters, Caribbean waters, and the Mona Passage. Small Craft Advisories remain in effect for the affected waters through at least late Friday night. Meanwhile, a drier air mass combined with moderate to high concentrations of Saharan dust will persist through the weekend, promoting hazy skies and periods of reduced visibility across the region.

BEACH FORECAST

Issued at 245 PM AST Thu Jul 9 2026

Wind-driven seas and breezy conditions will maintain a moderate risk of rip currents across most beaches of Puerto Rico and the U.S. Virgin Islands through the forecast period. As a result, life-threatening rip currents will remain possible in the surf zone each day, and beachgoers are urged to exercise caution. Additional beach hazards include the presence of Saharan dust, which will continue to promote hazy skies, reduced air quality, and warm to hot conditions during the peak afternoon hours. Sensitive groups should consider limiting prolonged outdoor exposure due to reduced air quality associated with Saharan dust, while everyone should stay hydrated and use caution if spending time at the beach.

FIRE WEATHER

Issued at 245 PM AST Thu Jul 9 2026

Dry and breezy conditions continued across southern Puerto Rico through the afternoon, with observations across the southern coastal plain indicating relative humidity values generally between 50 and 60 percent and frequent easterly wind gusts between 25 and 32 mph. Although localized rainfall occurred over parts of northwestern Puerto Rico, little to no wetting rainfall was observed across the southern fire weather zones, where critically dry fuels and persistent rainfall deficits remain in place.

A progressively drier air mass and moderate to locally high concentrations of Saharan dust will continue to overspread the region through tonight and persist into the weekend. Breezy easterly winds and low humidity will maintain favorable conditions for wildfire spread, with the greatest fire danger expected on Friday and Saturday as the drier air mass becomes firmly established over the region. The Fire Danger Statement remains in effect for portions of southern Puerto Rico today, and additional fire weather products may be needed through the weekend if dry and windy conditions persist.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007- 008-010-011.

VI...None. AM...Small Craft Advisory until midnight AST Friday night for AMZ711- 733-741.

Small Craft Advisory until 6 AM AST Friday for AMZ712-735.