textproduct: San Juan

Short Term(Today through Tuesday)

Issued at 336 AM AST Sun Jun 7 2026

Overnight conditions remained generally tranquil across Puerto Rico and the U.S. Virgin Islands. High-level cloudiness streamed across portions of the region, while patches of low-level clouds moved intermittently across the local waters and nearby coastal areas. In addition, the leading edge of a Saharan Air Layer began moving across the northeastern Caribbean, resulting in slightly hazy skies overnight. Temperatures remained warm, with minimum temperatures ranging from the upper 70s to lower 80s across coastal and urban areas and from the lower 70s across the higher elevations. Although most locations remained dry, a few passing showers were observed from time to time across portions of the surrounding waters, with little to no impact over land areas.

A moist and hazy weather pattern is forecast across Puerto Rico and the U.S. Virgin Islands today as moisture associated with a tropical wave moving across the Caribbean combines with the leading edge of a Saharan Air Layer intrusion spreading across the region. At the surface, a broad high pressure system over the central Atlantic will maintain southeasterly winds across the local islands. The presence of Saharan dust particles across the area has resulted in warmer overnight temperatures, with minimum temperatures remaining in the lower 80s across coastal and urban areas and in the lower 70s across the higher elevations. Therefore, the combination of tropical moisture and warm temperatures will support heat conditions rapidly increasing across the islands. As a result, heat indices are forecast to reach between 111 and 114 degrees across isolated areas of north- central Puerto Rico and portions of the interior northwestern quadrant. Therefore, a Heat Advisory remains in effect for coastal areas of Puerto Rico, including Culebra, Vieques, and the U.S. Virgin Islands. Meanwhile, the available moisture combined with daytime heating and lingering instability will support shower and thunderstorm development this afternoon, particularly across northwestern Puerto Rico. Periods of moderate to locally heavy rainfall may result in ponding of water on roads and in poor drainage areas, while thunderstorms cannot be ruled out, with the strongest activity.

Global model guidance from both the GFS and ECMWF continues to indicate a rapid drying trend beginning tonight, as a drier air mass, accompanied by a higher concentration of Saharan dust, filters into the region. The NASA Goddard Earth Observing System Model continues to suggest a higher concentration of Saharan dust particles lingering across the region through at least Tuesday morning. Therefore, Monday and Tuesday are expected to feature hazy skies, at times reduced visibility, and limited shower activity across the local islands. Additionally, model guidance suggests lower moisture values across the 700-500 mb layer and warmer temperatures aloft near 500 mb, resulting in a more stable weather pattern and limiting widespread shower development. Southeasterly winds will persist through Monday due to the presence of the broad surface high pressure over the central Atlantic. As the high pressure strengthens and expands across the Atlantic basin, winds are forecast to gradually become more easterly by Tuesday. Although widespread thunderstorm activity is not anticipated, one or two thunderstorms cannot be completely ruled out each afternoon across western Puerto Rico, where local effects and daytime heating maximize. Periods of reduced visibility and degraded air quality conditions will remain possible, particularly for sensitive groups. Overall, warm to hot conditions, hazy skies, and limited shower activity are expected through Tuesday as the Saharan Air Layer remains across the northeastern Caribbean.

Long Term(Wednesday through Sunday)

Issued at 336 AM AST Sun Jun 7 2026

he long-term forecast remains on track, with Thursday being the wettest day of the period. A surface high pressure across the central Atlantic will weaken due to its interaction with a low pressure in the northern Atlantic, weakening the local pressure gradient and low-level winds. However, local pressure gradient is likely as another surface high builds in the Western Atlantic by Friday, with winds strengthening and resulting in breezy to locally windy conditions. A drier airmass, along with some patches of moisture, should move on Wednesday, with below into near climatological normal moisture content across the CWA (PWATs between 1.4 and 1.6 inches), with limited shower activity. However, the latest model solutions continue to suggest an increase in moisture content on Thursday, as a tropical wave approaches the Caribbean Basin and an upper-level trough deepens into the tropics. Although the latest deterministic guidance of the GFS and ECMWF is tending to typical and near above-normal PWAT values (1.6 - 1.8 inches), ensemble members suggest a clear increase in moisture content on both low and mid levels (between 70 and 80%). Additionally, the proximity of the trough should cool mid-level temperatures (500 mb temperature dropping between -7 and -8 degrees Celsius), allow cloud growth and ventilation, which supports deep convection activity. Hence, the most likely scenario for Thursday is for isolated to scattered showers moving over windward sections of the islands throughout the day, while afternoon convection should concentrate over interior and northwestern Puerto Rico. Additionally, local island streamers may develop, including the San Juan streamer. Rainfall accumulations across the aforementioned areas may lead to ponding of water over roadways and poorly drained areas, along with urban and small stream flooding. In addition to flooding, other hazards that can be expected are gusty winds and lightning. Although the tropical wave should remain south of the CWA and move westward across the Caribbean Basin, lingering moisture and "troughiness" associated with the trough could enhance shower and thunderstorm activity on Friday afternoon, though the flooding chance should remain limited over northwestern portions of Puerto Rico. By Saturday, the CWA should be under the subsidence side of the trough, while a drier airmass filters into the region. Although daytime heating and local effects may induce afternoon convection, this should remain shallow and isolated.

As mentioned in the previous discussion, guidance continues to suggest near above normal 925 mb temperatures under an east- southeast wind flow. With the available moisture, heat indices will likely exceed 100 degrees Fahrenheit across urban and coastal areas of the islands, particularly on Thursday and Friday. Therefore, the heat risk should increase to elevated levels, meaning that most individuals without adequate hydration and/or effective cooling, Heat Advisories cannot be ruled out.

AVIATION

(06Z TAFS) Issued at 336 AM AST Sun Jun 7 2026

VFR conditions will prevail across all TAF sites. HZ associated with Saharan dust particles will reduce VIS.SE winds will increase from 07/13Z to 15-20 kt with higher gusts and sea breeze. SHRA and TSRA development is expected across western Puerto Rico, affecting mainly TJBQ between 07/18Z and 07/22Z. Brief MVFR conditions, reduced VIS, and lower CIGs are possible with the strongest activity. Winds will gradually diminish after 07/23Z.

MARINE

Issued at 336 AM AST Sun Jun 7 2026

A weak surface high pressure over the western Atlantic will merge with a broad surface high over the eastern Atlantic during the next few days. Two weak tropical waves will pass quickly south of the region through tonight, with mostly passing showers expected across the local waters. Moderate to locally fresh east to southeast trades are expected to continue across portions of the Caribbean and eastern waters of the islands through at least Monday. Locally higher winds due to the sea breeze are expected over the Atlantic waters just north of Puerto Rico during the afternoon hours. Moderate trades are expected to prevail for most of the workweek as the surface high moves over the Azores and a weak frontal boundary lingers over the southwestern Atlantic. Hazy skies due to moderate concentrations of Saharan dust will persist across the region through Tuesday.

BEACH FORECAST

Issued at 336 AM AST Sun Jun 7 2026

A moderate risk of life-threatening rip currents will continue across the north and east/southeast facing beaches of PR and St. Croix through at least Monday. Moderate concentrations of Saharan dust will persist over the region through early in the workweek. As winds and seas diminish through midweek, a low risk of rip currents is expected across all the islands. However, life- threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. Beach goers should always exercise caution regardless if the risk is low.

FIRE WEATHER

Issued at 336 AM AST Sun Jun 7 2026

A tropical wave will move across the region during the morning and early afternoon hours. Therefore, RH % values will remain in the mid to upper 60s and even higher with the presence of the moisture. Winds will remain from the southeast at 15 mph with gusty winds. Given the expected conditions the fire danger threat today remains none to low.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon for PRZ001>003-005-007-008-010>013.

VI...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon for VIZ001-002.

AM...None.