textproduct: San Juan

KEY MESSAGES

Issued at 134 AM AST Tue Jul 7 2026

* Dangerous heat will remain the primary weather hazard through the end of the workweek. A Heat Advisory is in effect today, and additional advisories may be needed later this week. Heat- related illnesses are possible without proper hydration, cooling, and frequent breaks.

* A fast-moving tropical wave will bring the best chance for showers and isolated thunderstorms on Wednesday. Ponding of water on roads, localized flooding, and dangerous cloud-to- ground lightning will be possible.

* Saharan dust will continue to degrade air quality and reduce visibility through much of the week, with only a brief improvement on Wednesday.

* Breezy easterly trade winds will maintain hazardous marine and beach conditions, including a moderate risk of rip currents at many local beaches.

Short Term(Today through Thursday)

Issued at 134 AM AST Tue Jul 7 2026

Extensive high-level cloudiness associated with an upper-level low northwest of the region continued streaming northeastward across the islands, limiting nocturnal cooling. Many coastal locations, along with a few inland sites, only fell to around 80 to 82 degrees, providing little overnight relief and increasing heat stress, especially for those without adequate cooling.

Today, breezy easterly trade winds will continue to bring a few passing showers across windward areas, with only a very localized afternoon shower possible over western Puerto Rico. However, moderate to high concentrations of Saharan dust and persistent dry mid-level air will continue to suppress significant rainfall while maintaining hazy skies and degraded air quality. Afternoon temperatures in the upper 80s to lower 90s, combined with typical to above-normal low-level moisture, will produce dangerous heat indices. Consequently, another Heat Advisory has been issued from 10 AM to 5 PM AST for lower elevations, coastal and urban areas of Puerto Rico, including Vieques and Culebra, as well as the U.S. Virgin Islands. Heat-related impacts will remain the primary weather hazard.

The axis of a fast-moving tropical wave is forecast to cross the region tonight, with deeper moisture spreading over the islands on Wednesday. As a result, scattered showers and isolated thunderstorms will become more common than in recent days. Ponding of water on roads and in poorly drained areas will be possible, while the potential for urban and small-stream flooding will remain limited. Frequent lightning will accompany the strongest thunderstorms. Warm conditions will persist, although increased cloud cover and lower Saharan dust concentrations should make dangerous heat less widespread.

By Wednesday night into Thursday, another surge of much drier air and Saharan dust will quickly overspread the region, returning a hot, very dry, and hazy weather pattern with little to no rainfall expected. Dangerous heat will once again become the primary weather hazard, and this pattern is expected to persist through the end of the workweek.

Long Term(Friday through Tuesday)

Issued at 134 AM AST Tue Jul 7 2026

Dry and mostly stable conditions are expected through the upcoming weekend and into early next week. A surface high north of the region will maintain generally east to east-southeasterly winds, with a brief shift to the northeast possible on Sunday due to an induced surface trough. Another surface high over the central Atlantic will strengthen the easterly flow again by early next week.

A drier air mass and moderate to high concentrations of Saharan dust will continue filtering into the region, limiting shower activity. Both the GFS and ECMWF indicate precipitable water values falling below climatological normals through the weekend, while forecast soundings show an unusually dry lower atmosphere. Although an upper-level low may linger nearby, the environment should remain unfavorable for sustained convection. Any showers that develop will be brief, fast-moving, and produce minimal impacts.

Hazy skies, reduced visibility, and degraded air quality will persist as Saharan dust continues across the region. Meanwhile, above-normal temperatures and sufficient low-level moisture will maintain dangerous heat, with heat indices likely exceeding 102F across urban, coastal, and lower-elevation areas. Warm overnight temperatures will provide little relief, allowing cumulative heat stress to persist into early next week.

AVIATION

(06Z TAFS) Issued at 134 AM AST Tue Jul 7 2026

VFR conditions will prevail at all TAF sites. Moderate to locally high concentrations of Saharan dust will continue to produce HZ and occasional VIS reductions, gradually improving overnight ahead of an approaching tropical wave. Brief VCSH are possible near TJSJ and TJBQ between 07/16-22Z, then near TJSJ and the USVI terminals after 07/22Z. E-ESE winds will increase from 6-12 kt to 16-22 kt with higher gusts between 07/13-22Z, diminishing to 8-14 kt after 07/22Z.

MARINE

Issued at 134 AM AST Tue Jul 7 2026

A broad surface high pressure over the central Atlantic will maintain moderate to fresh east to east-southeast winds and choppy seas through the end of the workweek. A fast-moving tropical wave will briefly increase showers and isolated thunderstorms late tonight into Wednesday before drier, dustier conditions return by Wednesday night. Moderate to high concentrations of Saharan dust will continue to produce hazy skies and occasional visibility reductions.

BEACH FORECAST

Issued at 134 AM AST Tue Jul 7 2026

A moderate risk of rip currents will persist at most local beaches through the end of the workweek as persistent moderate to fresh easterly winds maintain hazardous surf conditions. Life- threatening rip currents can still occur at beaches with a low risk, especially near jetties, piers, groins, and reefs.

Dangerous heat will continue each afternoon, increasing the risk of heat-related illnesses for beachgoers. A few thunderstorms may develop on Wednesday as a tropical wave moves across the region. If thunder roars, go indoors. Seek shade often, stay hydrated, and avoid prolonged sun exposure during the hottest part of the day.

FIRE WEATHER

Issued at 134 AM AST Tue Jul 7 2026

Higher humidity and a passing tropical wave will make weather conditions less supportive of rapid wildfire growth through Wednesday. Nevertheless, critically dry vegetation and persistent soil moisture deficits will continue to favor wildfire development, and any ignition could still spread through the available fine fuels despite fire weather thresholds not being met. As drier air and Saharan dust return late Wednesday into Thursday, weather conditions will once again become more favorable for wildfire growth through the end of the workweek. Residents and visitors should avoid outdoor burning and use extreme caution with any activity capable of producing sparks or open flames.

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.