textproduct: San Juan

KEY MESSAGES

Issued at 228 PM AST Wed Jul 1 2026

* Low to moderate concentrations of Saharan dust will persist through at least early Friday before increasing again for the 4th of July holiday.

* Limited shower activity is expected across the islands each day. However, localized afternoon showers and a few isolated thunderstorms remain possible across central and western Puerto Rico.

* Warm to hot conditions will continue through the next several days, with heat indices reaching or exceeding 100F across urban and low-lying areas.

* Winds are expected to increase over the weekend, accompanied by building seas. As a result, the risk of rip currents is expected to increase to moderate along most beaches across the islands.

Short Term(This evening through Friday)

Issued at 228 PM AST Wed Jul 1 2026

A dominant Saharan Air Layer (SAL) that earlier in the week restricted deep convection is gradually filtering westward, leading to a temporary drop in dust concentrations. However, low-to-moderate concentrations will persist through Friday, maintaining slightly hazy skies, before a thicker plume of Saharan dust returns late Friday night ahead of the holiday weekend. The lingering weak SAL will cause moisture content to fluctuate near seasonal levels, with precipitable water values ranging from 1.40 to 1.80 inches through the rest of the workweek. At the same time, a lingering upper-level cut-off low just north of the region continues to provide modest instability. A surface high pressure over the central Atlantic will maintain generally east-southeasterly winds between 15 and 20 mph.

The primary weather impacts through Friday will be from high daytime heat risks and localized afternoon convection. Mostly sunny skies and recovering low-level moisture will drive daytime maximum temperatures into the upper 80s and lower 90s, pushing heat index values to near 105F or higher across coastal, urban, and lower elevation areas. Meanwhile, the erosion of the trade wind inversion will allow for brief, fast-moving morning showers across the windward coasts. During the afternoons, daytime heating combined with sea-breeze convergence and local topographic effects will trigger scattered showers and isolated thunderstorms, mainly across the central and west/northwestern municipalities of Puerto Rico. Periods of moderate to heavy rainfall from these showers could cause localized urban and small-stream flooding, as well as ponding of water on roads and in poor drainage areas. Across the U.S. Virgin Islands and the eastern half of Puerto Rico, little to no rainfall is anticipated.

Long Term(Saturday through Wednesday)

Issued at 332 AM AST Wed Jul 1 2026

A transition from relatively dry and hazy conditions to a more humid and unstable tropical pattern continues to be forecast. A surface high pressure over the central Atlantic will maintain generally southeasterly winds, while a lingering upper-level cut-off low will continue over the region and provide modest instability through the period. During the weekend, shallow moisture and a plume of Saharan dust will promote hazy skies, hot conditions, and limited rainfall. However, brief morning showers over eastern Puerto Rico and isolated afternoon convection across the western interior and northwestern Puerto Rico remain possible due to local effects and daytime heating. To start the workweek, increasing mid-level moisture will support more active afternoon convection across western and northwestern Puerto Rico as Saharan dust gradually decreases. By late Monday and Tuesday, a tropical wave is expected to bring a surge of tropical moisture, which, along with favorable upper-level dynamics, will increase widespread showers and isolated thunderstorms. This can result in localized ponding of water on roads and in poor drainage areas. However, concentrations of Saharan Dust will continue to filter over the region to start the workweek and through midweek. Conditions will once again dry out on Wednesday as Saharan Dust continues. Warm to hot conditions will persist throughout the period as heat index values are expected to reach and surpass the 100s over coastal and lower elevations areas.

AVIATION

(18Z TAFS) Issued at 228 PM AST Wed Jul 1 2026

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. However, SCT SHRA and +TSRA expected to develop in and around TJBQ btw 01/18-22z, causing tempo MVFR conds. HZ due to minor to moderate concentrations of Saharan dust expected through the period, but VSBY should remain P6SM. The 01/12z TJSJ sounding indicated ESE winds up to 21 kt blo FL100.

MARINE

Issued at 228 PM AST Wed Jul 1 2026

Surface high pressure over the central and eastern Atlantic, combined with a frontal low over the western Atlantic, will promote moderate east to east-southeast winds. Across the Atlantic waters and local passages, winds could become locally fresh at times, and small craft should exercise caution. Seas will generally remain between 2 and 4 feet, with locally higher seas over exposed waters through Friday. By the weekend, winds will increase to moderate to fresh, and seas will build to around 4 to 6 feet. Additionally, low to moderate concentrations of Saharan dust are expected through Friday before a thicker plume with moderate to high concentrations arrives late Friday night and persists through the holiday weekend.

BEACH FORECAST

Issued at 228 PM AST Wed Jul 1 2026

The risk of rip currents is forecast to remain low through the rest of the workweek. However, life-threatening rip currents can still occur near jetties, reefs, and piers. Therefore, beachgoers are encouraged to remain cautious. Beginning Saturday, the risk of rip currents is expected to increase to moderate, meaning life- threatening rip currents will become possible in the surf zone as winds increase and seas gradually build.

Additional beach hazards include the presence of Saharan dust, especially during the weekend, which will result in hazy skies and reduced air quality, warm to hot conditions during peak heating hours, and isolated thunderstorms, particularly across the northwestern beaches of Puerto Rico each afternoon.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...None.