textproduct: San Juan

KEY MESSAGES

Issued at 122 AM AST Fri Aug 7 2026

- Today, expect hot and hazardous conditions with above-normal temperatures and dangerous afternoon heat indices expected across Puerto Rico and the U.S. Virgin Islands. Additional heat products will likely be needed in the coming days.

- A drier and more stable weather pattern will persist through the weekend. Limited rainfall is expected, allowing drought conditions to continue worsening across Puerto Rico and the U.S. Virgin Islands. Moderate concentrations of Saharan dust are expected to arrive late this weekend, resulting in hazy skies and occasional reductions in visibility.

- Elevated fire weather conditions will continue today across southern and southwestern Puerto Rico due to critically dry fuels, low relative humidity, and breezy easterly winds. A Fire Danger Statement is in effect, and residents should avoid outdoor burning and activities that could generate sparks or open flames.

Short Term(Today through Sunday)

Issued at 122 AM AST Fri Aug 7 2026

Overnight conditions remained relatively quiet and similar to the past few nights. Partly cloudy skies prevailed across the region, with temperatures along coastal areas in the upper 70s to lower 80s and in the upper 60s to lower 70s across the higher terrains. Winds remained variable.

For today and Saturday, similar weather conditions are expected as a relatively dry and stable air mass remains over the region. Precipitable water and mid-level moisture will generally fall in the below 2 standard deviation and in the 25 percentile scale today, with patches of moisture increasing precipitable water to slightly near normal values on Saturday. Brief passing showers may reach windward areas during the morning, followed by isolated afternoon showers across interior and western/southwestern Puerto Rico due to daytime heating and local effects. Nevertheless, relatively dry air in the mid-levels should limit the coverage and duration of deeper convection. Saharan dust will also begin filtering into the region on Saturday, with moderate concentrations expected to further suppress rainfall activity. The main impacts through Saturday will be excessive heat, particularly across coastal and urban areas, and an elevated fire danger. High temperatures in the upper 80s to lower 90s will result in heat indices reaching advisory criteria across portions of the coastal and urban areas. Meanwhile, dry conditions combined with increasing easterly winds will favor an elevated potential for fires, particularly across the dry southern sectors of Puerto Rico. Therefore, a Heat Advisory and Fire Danger Statement remains in effect. Additionally, due to the limited rainfall activity, we forecast drought conditions to continue worsening across Puerto Rico and the U.S. Virgin Islands.

As we head toward the end of the weekend, precipitable water values and mid-level moisture should also increase to near-normal values as an approaching tropical wave reaches the region. However, Saharan dust concentrations are expected to increase further on Sunday. Despite the increase in moisture associated with the tropical wave, the presence of Saharan dust and a generally stable environment should significantly limit shower and thunderstorm development. Therefore, rainfall activity should remain limited, and no flooding risk is anticipated at this time. Hot and humid conditions will persist, with Saharan dust also resulting in hazy skies across the region.

Long Term(Monday through Friday)

Issued at 122 AM AST Fri Aug 7 2026

For the long-term period, a warm pattern is forecast through the first part of the period. The 12Z NASA GEOS-5 aerosol optical depth (AOD) guidance indicates a dense Saharan Air Layer (SAL) plume dominating the northeastern Caribbean early in the period. This high concentration of Saharan dust will promote strong radiative heating and warmer overnight temperatures. As a result, above-normal minimum and maximum temperatures will persist, particularly across coastal and urban areas. Meanwhile, an upper-level high pressure centered near 250 mb and extending across the eastern Caribbean will promote cirrus advection and periods of high-level cloudiness across the area on Monday. Therefore, residents are urged to stay tuned for possible heat-related alerts. Conditions will remain fairly similar through Tuesday morning, with warm temperatures continuing across the area but with lower concentrations of Saharan dust. A rapid change in the weather pattern is expected by Tuesday afternoon as surface high pressure strengthens north of the region. The resulting tight pressure gradient will induce a strong low-level easterly wind surge, promoting breezy to windy conditions across the local islands and surrounding waters.

Another pattern transition is expected by midweek as the axis of an easterly tropical wave approaches the local area on Wednesday, increasing column moisture and pushing precipitable water (PWAT) values toward 2.0 inches. According to the latest global model guidance, the peak in moisture is expected between Wednesday afternoon and Thursday morning. Depending on the extent of cloud cover and early-day convective activity, sufficient insolation combined with the moist boundary layer could make Wednesday the warmest day of the period. Nevertheless, local diurnal heating and sea-breeze convergence will promote afternoon convection, particularly across interior and western Puerto Rico. The tropical wave will maintain elevated low-level moisture into Thursday; however, forecast confidence regarding rainfall intensity and coverage remains low, as a drier air mass behind the wave axis could quickly move into the region and limit organized convection. By Friday, a more typical trade-wind pattern is expected to return, with lingering low-level moisture supporting brief passing showers across windward areas. Overall, above-normal temperatures and periods of elevated to significant heat risk are expected to persist through much of the extended period.

AVIATION

(06Z TAFS) Issued at 122 AM AST Fri Aug 7 2026

VFR conditions across all TAF sites. VCSH will develop over the interior and western PR, VCTS possible. Brief periods of MVFR condt possible near TJBQ and TJPS from 07/17Z trough 07/23Z. Winds will remain from the E-NE around 10 to 15 kts and occasional higher gusts.

MARINE

Issued at 122 AM AST Fri Aug 7 2026

A broad surface high will maintain moderate easterly winds today, with seas of 3 to 5 feet, occasionally reaching 6 feet. Winds will increase late tonight, with breezy to windy conditions and choppier seas this weekend, strongest Sunday into Monday. Afternoon thunderstorms may briefly produce gusty winds and locally rough seas. Saharan dust may also reduce visibility through the weekend.

BEACH FORECAST

Issued at 122 AM AST Fri Aug 7 2026

A moderate risk of rip currents continues along the north-facing beaches of Puerto Rico and will expand to more east and southeastern beaches over the weekend as easterly winds strengthen. The risk is expected to decrease early next week. Heat remains the primary beach hazard, while isolated thunderstorms over western Puerto Rico may produce dangerous cloud-to-water lightning each afternoon.

FIRE WEATHER

Issued at 122 AM AST Fri Aug 7 2026

Once again, elevated fire weather conditions for today across the southern and southwestern Puerto Rico, where critically dry fuels, low relative humidity, and breezy easterly winds continue to support an increased risk for wildfire ignition and spread. Relative humidity values are expected to fallen into the upper 40s to lower 50s across portions with sustained winds around 15 to 20 mph, with higher gusts. Although isolated showers remain possible across the interior and western sections of Puerto Rico through late afternoon, rainfall coverage and amounts are expected to be insufficient to provide meaningful relief over the southern coastal plains, where fuels remain critically dry.

A drier and more stable weather pattern will established through the weekend as mid-level ridging strengthens and moisture decreases. Easterly trade winds will remain breezy each day, while afternoon minimum relative humidity values are expected to trend lower, particularly across southern Puerto Rico and the U.S. Virgin Islands. Combined with ongoing rainfall deficits and critically dry fine fuels, these conditions will support an elevated to locally critical fire weather threat each afternoon, especially across the southern and southwestern coastal plains of Puerto Rico. Residents and visitors should continue to avoid outdoor burning and exercise caution with activities capable of producing sparks or open flames, as favorable conditions for wildfire ignition and rapid spread are expected to persist through the weekend.

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.