textproduct: San Juan

KEY MESSAGES

Updated at 247 PM AST Thu May 28 2026

* Afternoon showers and isolated thunderstorms developing over interior to western PR. Ponding of water over roadways and poorly drained areas along with a flooding risk continues.

* A gradual trend toward more stable conditions is expected tomorrow into the weekend as a Saharan Air Layer (SAL) continues to filter in.

* Saharan dust concentrations will continue to gradually increase during the next few days, particularly late in the weekend into early next week. This will promote hazy skies, reduce visibilities and may also help limit shower activity at times. Sensitive groups should follow medical recommendations.

* Warmer than normal conditions are expected tomorrow and into the weekend due to SE winds. This pattern will elevate the heat risk across urban, coastal, and lower-elevation areas.

Long Term(Sunday through next Wednesday)

Issued at 247 PM AST Thu May 28 2026

During the long-term forecast period, a broad surface high pressure over the central Atlantic will remain the dominant weather feature across the region. This pattern will maintain southeasterly winds between 10 and 15 mph Sunday into Monday, becoming breezier by Tuesday. In addition, higher 250 mb heights and warmer 500 mb temperatures will promote a more stable atmospheric pattern across the northeastern Caribbean most of the forecast period.

By Sunday, moderate concentrations of Saharan dust will continue to affect the islands, resulting in hazy skies and reduced air quality. At the same time, moisture levels are expected to remain near seasonal values as patches of moisture move through the trade wind flow, with precipitable water (PWAT) values ranging between 1.50 and 1.65 inches. Although overall conditions will remain relatively stable, local effects and diurnal heating will continue to support afternoon showers and isolated thunderstorms across northwestern Puerto Rico. The strongest activity may produce brief periods of moderate to heavy rainfall, isolated lightning, and gusty winds, leading to localized flooding concerns in urban and poorly drained areas.

By Monday and Tuesday, forecast models continue to indicate a notable drying trend across the northeastern Caribbean as a broader and denser Saharan Air Layer (SAL) spreads across the region with moderate to high concentrations. PWAT values are forecast to fall below normal, dropping below 1.40 inches and approaching the lower climatological percentiles for this time of year. This pattern will favor drier and more stable atmospheric conditions, limiting the development of widespread showers and thunderstorms across Puerto Rico. Any shower activity that develops will likely remain brief and primarily confined to western Puerto Rico due to local and diurnal effects.

By Wednesday and Thursday, patches of moisture are expected to return across the region, allowing PWAT values to recover closer to seasonal levels. This could slightly increase the potential for afternoon showers across portions of northwestern Puerto Rico. However, global model guidance continues to show limited upper-level support. Residents and visitors should continue to monitor the forecast for updates as they become available.

Another significant concern during the long-term period will be the persistence of warm to hot daytime temperatures. Guidance at the 925 mb level continues to indicate temperatures near or above the 75th percentile, particularly on Sunday. Limited cloud cover, hazy skies, and persistent southerly winds will continue to support a warming trend across the region. As a result, moderate to elevated heat risk conditions are expected to persist, and Heat Advisories may become necessary. Residents and visitors are encouraged to take precautions against heat-related illnesses by staying hydrated and limiting prolonged exposure to the sun. In addition, individuals sensitive to poor air quality should follow recommendations from local health authorities due to high Saharan dust concentrations.

AVIATION

(18Z TAFS) Issued at 247 PM AST Thu May 28 2026

Mainly VFR conditions across the terminals. However, afternoon SHRA/TSRA is developing across western PR through around 28/22Z, this can result in VCTS/-TSRA (possible TEMPO conds at TJBQ). Elsewhere, VCSH expected at times. HZ due to Saharan dust continue during the period, with reduced VIS (6 to 8 SM) possible at times. E- ESE winds at 15-20 kt, with higher gusts and sea breeze variations, decreasing after 28/23z.

MARINE

Issued at 247 PM AST Thu May 28 2026

Seas are expected to remain around 5 to 6 feet over the Atlantic waters and below 4 feet nearshore, as easterly winds gradually diminish through Friday. Regardless, choppy seas are posible in some areas over the offshore Atlantic waters as a high pressure system remains over the central Atlantic. Mariners should also remain alert for afternoon thunderstorms developing near the western coastal waters of Puerto Rico, mostly today, which may produce locally higher winds, and dangerous lightning. Low concentrations of saharan dust will result in hazy skies and a slight reduction in visibility through at least early next week.

BEACH FORECAST

Issued at 247 PM AST Thu May 28 2026

A moderate risk of rip currents (life-threatening rip currents are possible in the surf zone) will persist throughout the workweek, mainly for northern and eastern beaches. A low risk of rip currents will continue elsewhere. However, even if the risk for rip currents is low, life-threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. A low to moderate risk of rip currents will continue during the next few days. Concentrations of saharan dust will continue to increase as we head towards the weekend and next workweek, this will result in hazy skies and deteriorated air quality. Afternoon convection can develop each day, mainly across western PR. For additional information, visit: weather.gov/beach/sju.

SJU WATCHES/WARNINGS/ADVISORIES

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