textproduct: San Juan

KEY MESSAGES

Updated at 250 PM AST Mon Jun 1 2026

* High concentrations of Saharan dust will continue to result in hazy skies, poor air quality, and reduced visibilities through tomorrow. Another pulse of moderate concentrations is expected by Thursday.

* Hot temperatures continue to be forecast during the next few days with limited to elevated heat risks persisting particularly at lower elevations and urban areas of the islands.

* Limited moisture and shower activity will continue during the workweek, with a brief increase in moisture forecast by Wednesday.

Short Term(This evening through Wednesday)

Issued at 250 PM AST Mon Jun 1 2026

A tranquil weather pattern prevailed across Puerto Rico and the U.S. Virgin Islands today under the influence of a dense Saharan Air Layer (SAL). High concentrations of suspended Saharan dust resulted in hazy skies and reduced long-range visibility across the region. Rainfall activity was null, as the dry and stable air mass suppressed cloud development and precipitation. Meanwhile, warm to hot temperatures persisted throughout the day, supported by abundant sunshine and limited cloud cover.

Looking ahead, dry, stable, and hazy conditions will continue through Wednesday as the Saharan Air Layer remains established across the northeastern Caribbean. Although dust concentrations are expected to gradually decrease from their peak levels observed today, low to moderate concentrations will linger. The combination of mid-level ridging, a trade wind inversion, and lingering dry air will continue to inhibit significant convective development, keeping rainfall chances limited. Only a few brief trade wind showers may affect windward areas during the overnight and early morning hours, while isolated afternoon showers cannot be completely ruled out across western Puerto Rico.

By late Wednesday, an additional plume of moisture embedded within the easterly trades is forecast to move across the islands. This moisture increase may promote periods of enhanced cloudiness and a slight increase in the frequency of passing showers. However, weather conditions are expected to remain generally unfavorable for widespread or organized rainfall activity. As a result, warm temperatures, mostly dry weather, and hazy conditions are expected to persist through the remainder of the forecast period.

Long Term(Thursday through next Sunday)

Issued at 335 AM AST Mon Jun 1 2026

Overall, a drier weather pattern is expected to prevail throughout much of the long-term period, limiting shower activity across Puerto Rico and the U.S. Virgin Islands. A dominant mid-level ridge will continue to promote dry and stable conditions aloft. At the upper levels, an upper-level low will remain well east of the local islands and the Lesser Antilles, enhancing subsidence across the northeast Caribbean. Meanwhile, at the surface, a strong Azores High will continue to drive breezy southeasterly winds through early next week.

Under this pattern, mainly fair weather conditions are anticipated to persist, supported by below-normal precipitable water (PWAT) values of approximately 1.0 inch for this time of the year, particularly in early June. Even as drier air dominates, embedded patches of low-level moisture will filter into the area from time to time. This will bring brief, fast-moving showers to portions of eastern Puerto Rico and the U.S. Virgin Islands during the morning hours, followed by locally driven showers in the afternoon. The potential for isolated thunderstorms remains low, as mid-level temperatures at 500 mb are forecast to remain well above normal at a warm -4C. Consequently, any afternoon shower activity will be short- lived and confined to portions of central and northwestern Puerto Rico. The latest model guidance indicates that by Friday into Saturday, a weak tropical wave will pass well south of the area. While some peripheral moisture from this wave may reach the islands, impacts are expected to be minimal.

Furthermore, another plume of moderate Saharan Air Layer is forecast to arrive and persist through the upcoming weekend, resulting in hazy skies, reduced visibilities, and poor air quality. Sensitive groups, particularly individuals with respiratory conditions should take necessary precautions to limit outdoor exposure and seek medical recommendations.

AVIATION

(18Z TAFS) Issued at 250 PM AST Mon Jun 1 2026

VFR conditions will prevail during the next 24 hours. HZ and VSBY near 6SM due to Saharan dust over all TAF sites. Sfc winds will decrease to around 5 to 10 kt after 01/22Z. The ESE winds will gradually increase from 02/12Z.

MARINE

Issued at 250 PM AST Mon Jun 1 2026

A surface high will tighten the local pressure gradient, resulting in moderate to fresh east-to-east-southeast winds, promoting choppy seas across the regional waters throughout much of the week. Confused seas are also expected by midweek as a small northerly swell arrives. High concentrations of Saharan Dust will continue tonight and tomorrow. Trade wind showers are expected to increase by midweek, before another pulse of moderate Saharan Dust concentrations arrives by Thursday.

BEACH FORECAST

Issued at 250 PM AST Mon Jun 1 2026

Up to a moderate risk of rip currents (life-threatening rip currents are possible in the surf zone) will persist across the majority of exposed beaches of the islands. This is due to increasing winds and choppy seas (as well as a small northerly swell arriving by midweek). Even in areas where the risk for rip currents is low, life- threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. Always swim near a lifeguard and remember to heed the advice of the local beach patrol and flag warning systems.

High concentrations of Saharan Dust will continue to affect the area tonight and tomorrow. Less concentrations of Saharan dust are forecast by Wednesday as moisture associated with a trade wind perturbation increases the potential of rain (with passing showers across windward areas and afternoon convection over western PR). Another pulse of moderate Saharan Dust concentrations is forecast to arrive by Thursday.

SJU WATCHES/WARNINGS/ADVISORIES

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