textproduct: San Juan

KEY MESSAGES

Issued at 225 PM AST Mon Jul 6 2026

* The extreme heat risk will remain elevated throughout the week. Hot temperatures combined with the available moisture will increase the risk of heat-related illnesses, particularly for those spending prolonged periods outdoors or without adequate cooling.

* Moderate concentrations of Saharan dust will affect the islands through the middle of the week, returning once again by the second part of the week. Expect hazy skies, reduced visibility, and deteriorating air quality.

* Increasing winds will promote a moderate risk of life- threatening rip currents on several local beaches throughout the week. Life-threatening rip currents are possible. Swim near a lifeguard, heed beach warning flags, and follow the advice of local beach patrols.

* A weak tropical wave may bring beneficial rainfall, isolated thunderstorms, and locally heavy showers between late Tuesday night and early Wednesday. Localized flooding cannot be ruled out, although increasing winds should favor progressive showers and help limit widespread flooding. Continue to monitor the latest forecast for updates.

Short Term(This evening through Wednesday)

Issued at 225 PM AST Mon Jul 6 2026

The hot trend continues across the region, with a mix of sunshine and clouds at different layers of the atmosphere, resulting in sunny to partly cloudy skies at times. The mid- and upper-level clouds are associated with a low aloft near the Turks and Caicos Islands. Local network measurements showed moderate levels of suspended particles today, resulting in hazy skies and deteriorated air quality. We noted warmer-than-normal morning temperatures today, with afternoon temperatures climbing into the upper 80s and lower 90s, or even into the mid 90s, producing peak heat indices of 100-111F. East to east-southeast winds ranged from 10 to 20 mph with higher gusts and local sea-breeze variations, bringing a few showers across eastern PR this morning.

A Saharan Air Layer will create poor air quality, hazy skies, and reduced visibility, and will generally suppress widespread rainfall across Puerto Rico and the U.S. Virgin Islands through Tuesday. Temperatures are expected to stay above normal, particularly in urban and coastal areas. Thus, the islands will experience a warm-to-hot weather pattern through the short term, particularly from mid-morning to the afternoon, when Heat Advisories may be issued.

A weak tropical wave is expected to increase the Total Precipitable Water (TPW) and the potential for showers in the region from late Tuesday night to Wednesday morning. During this time, some showers and a few thunderstorms may develop. While this activity could provide beneficial rainfall, we do not expect widespread rainfall due to the unfavorable conditions surrounding the wave. Model forecasts suggest that drier conditions will return to the area by Wednesday afternoon or evening onward.

Long Term(Thursday through Monday)

Issued at 235 AM AST Mon Jul 6 2026

The long-term forecast remains on track, with no significant changes introduced since the previous discussion. A building surface high pressure system north of the region will maintain a tight pressure gradient, promoting breezy to windy conditions across the islands through the first half of the long-term period. Winds are expected to prevail from the east-east southeast through Saturday, before veering from the east-northeast from Sunday into Monday morning.

On Thursday, moisture associated with the northern periphery of a passing tropical wave will approach the region. Nonetheless, the bulk of the moisture from this wave is expected to remain well south of the area over the Caribbean Sea, keeping local impacts minimal. The latest precipitable water analysis indicates below-normal moisture for the period, with precipitable water (PWAT) values dropping to 1.25 to 1.30 inches on Thursday. Therefore, no significant flooding impacts are expected with this wave.

Following the passage of the wave, a mid-level ridge is expected to strengthen, promoting drier and more stable conditions through the remainder of the period. From Friday onward, a drier air mass will begin to filter into the region alongside a dense plume of the Saharan Air Layer (SAL). Moderate to high concentrations of dust will reach the area throughout the weekend, promoting hazy skies, reduced visibilities, and poor air quality. Sensitive groups, particularly those with respiratory issues or allergies, should take necessary precautions to limit outdoor exposure.

Conditions will remain very similar throughout the weekend, with a slight increase in moisture expected by the beginning of next week as another disturbance approaches the islands. Temperatures at 925 mb will remain within seasonal values during the period, with maximum temperatures reaching the upper 80s and low 90s across coastal and urban areas, and the low to mid-80s in the mountains. However, heat indices are forecast to reach or exceed 100F each afternoon. Residents and visitors are strongly urged to practice heat safety by staying hydrated, limiting strenuous outdoor activities, and taking frequent breaks in shaded or air-conditioned areas.

AVIATION

(18Z TAFS) Issued at 225 PM AST Mon Jul 6 2026

VFR conditions will persist for the rest of the period across all TAF sites. Persistent HZ across the TAF sites lowering VIS across the area until 06/17Z for TISX & TIST. Winds will remain from the E at 15 knots and gusty winds up to 25 knots, diminishing at 06/23Z up to 12 knots and increasing again at 07/14Z up to 15 knots and with gusty winds. Some VCSH are expected across TIST and TISX for late afternoon due to an increase in moisture from a tropical wave.

MARINE

Issued at 225 PM AST Mon Jul 6 2026

A high-pressure system over the central Atlantic will promote moderate to fresh east to east-southeast winds and choppy seas across the region throughout much of the week. A weak tropical wave will cross the Lesser Antilles around Tuesday, crossing the local islands around early Wednesday morning, which could increase the chance of thunderstorms. A dense Saharan Air Layer will continue to spread across the region throughout the week, lowering visibility and worsening air quality at times.

BEACH FORECAST

Issued at 225 PM AST Mon Jul 6 2026

Increasing east to east-southeast winds are expected to create hazardous beach conditions across most of Puerto Rico and the U.S. Virgin Islands. As a result, there will be a moderate risk of life-threatening rip currents at most local beaches throughout the week, especially as winds strengthen and surf becomes more energetic. Even at low-risk beaches, isolated life-threatening rip currents may still occur, particularly near jetties, groins, reefs, and piers.

Hot and humid conditions will continue each afternoon, with dangerous heat levels possible at the beaches. Isolated thunderstorms may also develop over portions of the islands, especially on Wednesday, with the passage of a weak tropical wave. If you hear thunder or see lightning, leave the beach immediately and seek shelter in a substantial building or hard-top vehicle. Stay hydrated, seek shade frequently, wear lightweight clothing, and limit prolonged sun exposure during the hottest part of the day.

FIRE WEATHER

Issued at 225 PM AST Mon Jul 6 2026

Fire weather conditions are improving today through Tuesday as humidity increases. However, critically dry fuels and soil moisture deficits will persist in parts of southern Puerto Rico, with KBDI values above 550, some exceeding 660. Fires that develop could spread through dry vegetation, particularly in the southern coastal plains, though increased humidity should reduce fire behavior. Residents and visitors should avoid outdoor burning and exercise caution when engaging in activities involving open flames.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>005-007- 008-010>013.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

AM...None.