textproduct: San Juan

KEY MESSAGES

Updated at 1258 PM AST Fri May 29 2026

* More stable conditions are expected as we head into the weekend as a Saharan Air Layer (SAL) continues to filter in, afternoon convection possible each day.

* Saharan dust concentrations will continue to gradually increase during the next few days, particularly late Sunday through Tuesday.

* Hazy skies and reduced visibility are forecast due to this Saharan dust. Sensitive groups, including people with respiratory conditions, may experience discomfort and should follow medical recommendations.

* Warmer than normal conditions are expected through at least early next week due to ESE winds. This pattern will elevate the heat risk across urban, coastal, and lower-elevation areas.

Short Term(This evening through Sunday)

Issued at 1258 PM AST Fri May 29 2026

Current satellite-derived precipitable water (PWAT) values indicate 1.45 to 1.7 inches (below normal to normal values) over the islands. This moisture is mostly limited to below 800 mb as a mid to upper level ridge continues to establish itself during the next few days. An upper level trough will also linger east of the Lesser Antilles during the period. At surface level, a broad high over the Atlantic will result in up to breezy E to ESE winds during the period, as it tightens the local pressure gradient. PWAT values are forecast to remain at below normal to normal values during the period as the steering flow continues to steer patches of both drier and more humid air towards the islands. Mainly passing showers are forecast for windward sectors while afternoon convection develops each day, particularly over interior to W-NW PR. Localized and isolated t-storms are possible each day over W-NW PR as cool 500 mb temperatures (-8 to -9 degrees C) remain over the region. A notable uptick in PWAT (still at normal values) is forecast for Sunday as moisture associated with a tropical wave reaches the islands.

Through the rest of the short term period and into the long term period (next workweek), Saharan dust concentrations are anticipated to rise, reaching moderate to locally high concentrations today into early Sunday. From late Sunday and into the long term period more widespread high concentrations are expected across the region as the peak of the event arrives. This will result in hazy skies and reduced air quality. Individuals in sensitive groups (such as those with respiratory conditions, young children, and older adults) should take appropriate precautions and limit prolonged outdoor exposure during this period. Warm to hot temperatures will persist through the weekend, especially across coastal and urban areas. An elevated heat risk is forecast for these areas each late morning to afternoon, particularly on Sunday. This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration.

Long Term(Monday through next Thursday)

Issued at 110 AM AST Fri May 29 2026

The inherited forecast remains largely unchanged. 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, bringing moderate to high dust concentrations. Precipitable water (PWAT) values are forecast to fall below normal values for this time of the year, dropping to around or below 1.25 inches, which is near the 25th percentile for this time of year. This pattern will promote drier and more stable atmospheric conditions, limiting the development of widespread showers and thunderstorms across Puerto Rico. Any shower activity that does develop is expected to remain brief and primarily confined to western Puerto Rico due to local and diurnal effects.

Midweek through Friday, patches of moisture are expected to gradually return across the region, allowing PWAT values to recover closer to seasonal levels. This may slightly increase the potential for afternoon showers across portions of northwestern Puerto Rico. However, global model guidance continues to indicate limited upper- level support, which should help restrict more organized or widespread convection. Residents and visitors should continue to monitor the forecast for the latest updates.

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. Limited cloud cover, hazy skies, and persistent southerly winds will continue to support a warming trend across the region, particularly on Monday. 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, seeking shade, and limiting prolonged exposure to the sun. In addition, individuals with respiratory illnesses or heightened sensitivity to poor air quality should follow recommendations from local health authorities due to the expected high concentrations of Saharan dust.

AVIATION

(18Z TAFS) Issued at 1258 PM AST Fri May 29 2026

Mainly VFR conditions across the terminals. Afternoon SHRA/TSRA can develop over western PR through around 29/21Z, this can result in VCTS/-TSRA. Elsewhere, limited VCSH expected at times. HZ due to Saharan dust will continue during the period, with reduced VIS (6 to 8 SM) possible. E-ESE winds at 12 to 16 kt, with higher gusts and sea breeze variations, decreasing after 29/23z with land breezes.

MARINE

Issued at 1258 PM AST Fri May 29 2026

A surface high over the central Atlantic will promote generally moderate to locally fresh east to east-southeast winds this weekend into early next week across the region. Based on the latest altimeter scans, seas remain between 3 and 5 feet, localized to 6 feet, across local Atlantic waters. Mariners must exercise caution as choppy seas could result in localized hazardous conditions for small craft. Besides the marine conditions, mariners should remain weather alert as afternoon showers and thunderstorms could move over the coastal waters of northwestern Puerto Rico today. Additionally, moisture content associated with a tropical wave approaching the Caribbean Basin will likely enhance shower and thunderstorm activity across the regional waters on Sunday. Hazards may include gusty winds, reduced visibility, and lightning. Moderate concentrations of Saharan dust will persist this weekend, becoming higher by late Sunday into Monday, resulting in hazy skies, reduced visibility, and poor air quality.

BEACH FORECAST

Issued at 1258 PM AST Fri May 29 2026

The moderate risk of rip currents should continue tonight, particularly across the northern and eastern beaches of Puerto Rico, including Culebra, and St. Croix in the U.S. Virgin Islands, with a low risk elsewhere. Beachgoers must exercise caution, as life- threatening rip currents remain possible along the beaches under moderate risk. This weekend, the risk should be lower across the islands. However, life-threatening rip currents often occur near groins, jetties, reefs, and piers. The risk should increase, once again, to a moderate risk by Monday and persist for the rest of the forecast period. In addition to rip currents, beachgoers should stay weather alert as showers and isolated thunderstorms could develop in the afternoon and move near coastal areas of northwestern Puerto Rico, bringing gusty winds and lightning. Moderate concentrations of Saharan dust will persist this weekend, with a dense layer reaching the islands by late Sunday into Monday, resulting in hazy skies, reduced visibility, and poor air quality.

SJU WATCHES/WARNINGS/ADVISORIES

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