textproduct: San Juan

KEY MESSAGES

Issued at 301 AM AST Mon May 25 2026

* Breezy to windy easterly conditions are expected today. Outdoor items could be blown around or damaged. Therefore, a Wind Advisory is in effect through this evening.

* Hazardous marine and coastal conditions will continue through at least tomorrow Tuesday. Small Craft Advisories remain in effect for most local waters, and a high risk of rip current is expected for many northern, eastern, and southeastern beaches of Puerto Rico and the U.S. Virgin Islands.

* Warm to hot conditions will persist through much of the week across the islands, with hotter conditions expected by the end of the week. Heat indices are expected to exceed 100 degrees across urban and coastal areas of Puerto Rico and the U.S. Virgin Islands, with a moderate to locally elevated risk of heat-related impacts.

* Afternoon showers and very isolated thunderstorms could still impact western portions of Puerto Rico despite the arrival of a drier airmass over the region today. Uptick of passing showers across windward coastal areas and smaller islands tonight.

* Minor to moderate concentrations of Saharan dust are forecast to arrive by midweek and persist into late week, resulting in hazy skies and possible reductions in air quality and visibility, especially for sensitive groups.

Short Term(Today through Wednesday)

Issued at 301 AM AST Mon May 25 2026

Breezy to windy easterly conditions will continue today as surface high pressure maintains a tight local pressure gradient across the northeastern Caribbean. Global models suggest that 925 mb winds will remain well above normal today, supporting gusty conditions at the surface, especially across coastal areas, higher elevations, and exposed locations. Outdoor items could be blown around or damaged, and tree limbs could be blown down. Therefore, a Wind Advisory is in effect through this evening.

A brief drying trend is expected today as precipitable water values drop sharply to near 1.3 inches, which is below normal for late May. Low- to mid-level moisture will also decrease, with 850-700 mb relative humidity values falling into the 30 to 40 percent range at times. Despite the arrival of this drier air mass, sufficient low- level moisture and local effects will still support afternoon showers and very isolated thunderstorms across western portions of Puerto Rico.

By late tonight into Tuesday, and continuing into Wednesday, moisture will increase again as tropical moisture associated with a tropical wave surge and an easterly perturbation moves into the region. Model guidance indicates precipitable water values rising back to near or above normal levels, generally around 2.0 inches or even slightly higher, with mid-level relative humidity increasing as well. This will support a wetter and more unstable pattern.

Although widespread significant rainfall is not anticipated at this time, the increase in moisture and instability on Tuesday and Wednesday will elevate the risk for urban and small-stream flooding. The highest rainfall potential should focus across western and interior Puerto Rico during the afternoons, as sea breeze convergence and local effects combine with potential thunderstorm activity. Eastern Puerto Rico, the U.S. Virgin Islands, and the smaller islands will see periodic passing showers embedded in the easterly trades.

Warm to hot conditions will persist through the period, with the hottest conditions expected by midweek. Heat indices are expected to exceed 100 degrees across urban and coastal areas of Puerto Rico and the U.S. Virgin Islands, resulting in a moderate to locally elevated risk of heat-related impacts. In addition, minor to locally moderate concentrations of Saharan dust are forecast to arrive by midweek. This may result in hazy skies and possible reductions in air quality and visibility, especially for sensitive groups.

Long Term(Thursday through Monday)

Issued at 301 AM AST Mon May 25 2026

The long-term forecast remains on track. At the surface, lingering moisture associated with a previous tropical wave will remain across the forecast area, with PWAT values around 2.10 inches. This pattern will promote a wetter and "muggy" weather pattern, supporting shower development across the islands with periods of moderate to heavy rainfall. A broad high pressure extending into the central Atlantic will maintain east-southeasterly winds, promoting warm conditions across northern and western Puerto Rico. Additionally, the NASA Goddard Earth Observing System model continues to indicate a significant pulse of Saharan Air Layer moving into the region through the day. This increase in suspended dust particles will result in hazy skies and warmer daytime temperatures. Stable conditions at the mid-levels due to a strengthening ridge aloft may gradually limit widespread thunderstorm activity, although local effects and available moisture will still support afternoon convection across the interior and northwestern Puerto Rico. Urban and small-stream flooding, ponding of water on roads, isolated lightning strikes, and gusty winds will remain possible with the strongest showers. Heat indices may also reach elevated levels across urban and coastal areas due to the combination of warm temperatures and high humidity.

From Friday through Sunday, the available moisture is forecast to migrate northward as a drier air mass filters into the northeastern Caribbean, lowering PWAT values generally between 1.60 and 1.80 inches. Surface winds will persist from the southeast as the Atlantic high pressure remains the dominant weather feature across the region. This pattern, combined with higher 925 mb temperatures and increasing Saharan dust concentrations, will promote a notable warming trend through the weekend. Under periods of limited cloud coverage, heat indices may rise between 108 and 111 degrees across northern, western, and urban coastal sections of Puerto Rico. Hazy skies and poor air quality may also affect sensitive groups, including individuals with respiratory conditions and allergies. Although a drier and more stable pattern is expected overall, local effects and daytime heating will continue to trigger afternoon convection each day, mainly across the northwestern quadrant of Puerto Rico. On Sunday, a slight surge of moisture may increase shower development once again, resulting in more active afternoon convection across portions of western Puerto Rico. On Monday, both the global GFS and ECMWF models suggest a significant drying trend, with precipitable water values dropping to around 1.2 inches. This drastic change will result from a large pulse of drier air associated with a Saharan Air Layer intrusion, enough to promote widespread hazy skies and a continued warm trend across the region.

AVIATION

(06Z TAFS) Issued at 301 AM AST Mon May 25 2026

Mainly VFR conds expected to prevail through the fcst period. Brief VCSH will remain possible across TJSJ/TIST/TISX thru the morning hrs, with afternoon SHRA/isol TSRA possible near TJBQ btw 18-22z. The 25/00z TJSJ sounding indicated E winds up to 24 kt blo FL060. Sfc winds generally E at 08-15 kt early, increasing aft 14z to 20-24 kt with gusts around 30-33 kt. Winds diminish slightly after 23z but remain breezy, with VCSH possible again across windward terminals.

MARINE

Issued at 301 AM AST Mon May 25 2026

Small Craft Advisories remain in effect for the offshore waters and local passages through Tuesday morning as moderate to locally strong easterly winds continue to generate choppy to rough seas of up to 7 feet. These conditions will persist through at least midweek as strong high pressure over the central Atlantic maintains a tight pressure gradient across the northeastern Caribbean. In addition, isolated afternoon thunderstorms near the western coastal waters of Puerto Rico may produce locally higher winds and seas.

BEACH FORECAST

Issued at 301 AM AST Mon May 25 2026

A high risk of rip currents, meaning life-threatening rip currents are likely in the surf zone, will continue through late tonight for the northern, eastern, northeastern, and southeastern beaches of Puerto Rico, as well as Vieques, Culebra, and the U.S. Virgin Islands. A moderate risk of rip currents, meaning life-threatening rip currents are possible in the surf zone, will persist across the remaining local beaches. The risk is expected to increase again across many exposed beaches Monday into Tuesday as easterly winds strengthen and the Atlantic pressure gradient tightens.

Beachgoers should heed the advice of local officials and beach safety personnel. Afternoon thunderstorms are also possible each day across western Puerto Rico and may produce dangerous lightning. For additional information and location-specific rip current forecasts, visit weather.gov/beach/sju.

FIRE WEATHER

Issued at 301 AM AST Mon May 25 2026

Little to no rainfall is anticipated across the southern sections of Puerto Rico today. Drier air is also expected to filter into the region, allowing relative humidity values to drop into the upper 40s to low 50s. Wind speeds may reach around 16 to 25 mph, with higher gusts. Furthermore, a Wind Advisory is in effect through this evening. KBDI values in Cabo Rojo remain above critical fire weather thresholds. Additionally, the 7-day percent of normal rainfall across the southern coastal plains is below 25%, with some locations even below 5%. Therefore, conditions will be favorable for the spread of wildfires along the southern coastal plains of Puerto Rico. A Fire Danger Statement (RFDSJU) has been issued.

SJU WATCHES/WARNINGS/ADVISORIES

PR...High Rip Current Risk through late tonight for PRZ001>003-005- 008-012-013.

Wind Advisory until 8 PM AST this evening for PRZ001>013.

VI...High Rip Current Risk through late tonight for VIZ001-002.

Wind Advisory until 8 PM AST this evening for VIZ001-002.

AM...Small Craft Advisory until 6 AM AST Tuesday for AMZ711-712-716- 723-726-733-741.