textproduct: San Juan

KEY MESSAGES

Issued at 200 PM AST Fri Jul 3 2026

* Moderate to high concentrations of Saharan dust will overspread the islands through the holiday weekend. Expect hazy skies, reduced visibility, deteriorating air quality, and an increased risk of respiratory impacts, especially for sensitive groups. * Elevated heat risk is expected each afternoon. Hot, humid conditions will increase the risk of heat-related illnesses, particularly for those spending prolonged time outdoors or without adequate cooling.

* A moderate risk of rip currents will develop across several local beaches beginning Saturday and persist through the middle of next week. Life-threatening rip currents are possible. Swim near a lifeguard, heed beach warning flags, and follow the advice of local beach patrols.

Short Term(This evening through Sunday)

Issued at 200 PM AST Fri Jul 3 2026

Another warm, hot, and humid day prevailed today, prompting the issuance of a Heat Advisory for most coastal and urban areas in the USVI and PR. The Advisory is in effect through 5 PM AST. Maximum temperatures are in the upper 80s and low 90s, and heat indices are around 102-111 degrees Fahrenheit along the coast and in urban areas. Winds were mainly from the east to east-southeast at 5 to 15 mph, with higher gusts and sea-breeze variations. A strong thunderstorm developed across the western sections due to local effects, diurnal heating, and sea breeze, resulting in downpours, frequent cloud to ground lightning and gusty winds.

The main threat for the rest of the afternoon is still excessive heat, with apparent temperatures from 100 to 111 degrees Fahrenheit, or even higher due to local effects at most coastal and urban sites. However, the amount of heat combined with the available moisture will result in another day of localized induced showers across the interior and west quadrants of PR and downwind of the USVI. Additional strong thunderstorms cannot be ruled out due to these local effects. This activity will promote ponding of water in roads and poorly drained areas, without ruling out urban and small stream flooding this afternoon.

The islands will experience an advective pattern through Sunday, with showers primarily driven by east to east-southeast winds each day. These showers will be most noticeable in the windward areas. Meanwhile, afternoon convection is expected to be limited in the interior and western parts of Puerto Rico, as well as downwind of the US Virgin Islands and El Yunque. However, on Sunday, we anticipate a relative increase in available moisture, which could lead to a slight increase in rainfall activity. It is important to note that a ridge pattern at mid-levels will restrict vertical development.

The islands will continue under a warm-to-hot weather pattern through the short term, especially from mid-morning into the afternoon, when Heat Advisories may be necessary.

A Saharan Air Layer (SAL) is expected to move into the region, bringing moderate dust concentrations later tonight into early Saturday, with potentially high concentrations impacting the US Virgin Islands as early as Saturday morning. By Saturday afternoon, this layer with high concentrations will extend to the rest of Puerto Rico, leading to a return to moderate concentrations by Sunday. This SAL will limit rainfall, resulting in hazy skies, reduced visibility, and poorer air quality.

Long Term(Monday through Friday)

Issued at 127 AM AST Fri Jul 3 2026

No major changes to the long term forecast. A Saharan Air Layer (SAL) with moderate to high concentrations of Saharan Dust will continue to filter over the islands to start the next workweek, these concentrations are forecast to persist through Wednesday. However, model guidance suggests that another plume of moderate to possibly high concentrations of Saharan Dust will reach the islands once again on Friday. Even with Saharan Dust filtering in and promoting hazy conditions, a humid and unstable pattern is still forecast as a tropical wave and its related moisture field arrive by midweek. A surface high over the Atlantic will continue during the workweek, promoting up to breezy E to SE winds (becoming breezy to windy later in the period).

An upper-level low will continue lingering north of the islands throughout much of the workweek with model guidance suggesting another upper-low reaching the area from the east to end the workweek, providing modest instability through the period. As patches of moisture continue to filter over the islands on Monday and Tuesday, precipitable water (PWAT) values will increase to high-end normal and above normal values. This will promote passing overnight and morning showers over eastern the eastern region and convective afternoon showers and t-storms across the western interior and northwestern Puerto Rico, as well as downwind of the local islands and El Yunque, due to local effects and diurnal heating. Most available moisture will be below 800 mb, with the exception of Wednesday where available moisture reaches the mid to upper levels.

By late Tuesday and Wednesday, a tropical wave is expected to bring a surge of tropical moisture (with above normal PWAT), which, along with favorable upper-level dynamics, will increase widespread showers and isolated thunderstorms, as well as increase flooding and lightning risks. However, concentrations of Saharan Dust will continue to filter over the region. Conditions will once again dry out on Thursday as PWAT values decrease to below normal to low-end normal values, however a brief window with less concentrations of Saharan Dust is forecast, giving way to a more typical summer pattern (under breezy to windy flow) with overnight and morning passing showers as well as afternoon showers and isolated t-storms over W Puerto Rico. Even drier air with another plume moderate to possibly high concentrations of Saharan Dust will reach the islands on Friday, prompting a drier and hazy pattern. Warm to hot conditions will continue during the workweek as heat index values are expected to reach and/or surpass the 100s over coastal and lower elevation areas of the islands.

AVIATION

(18Z TAFS) Issued at 200 PM AST Fri Jul 3 2026

Mainly VFR conditions are expected to prevail across all terminals during the next 24 hours. However, TSRA/VCTS are affecting TJBQ btw 03/18-21z, causing intermittent MVFR/IFR conds. ESE winds around 15 to 20 kts with gusts near 24 to 28 kts, around 10 kts overnight, increasing again aft 03/13-14z. HZ will increase 04/09Z at USVI TAF sites and after 04/12-14Z across PR TAF sites reducing VIS.

MARINE

Issued at 200 PM AST Fri Jul 3 2026

A surface high pressure over the central Atlantic, interacting with a weak tropical wave moving westward across the Caribbean Sea well to the south of the islands, will maintain moderate to locally fresh east to east-southeast winds through the weekend. As a result, seas will remain moderate to locally choppy, particularly across the Caribbean waters and local passages. Meanwhile, a Saharan Air Layer will overspread the region through the weekend, reducing visibility at times.

BEACH FORECAST

Issued at 200 PM AST Fri Jul 3 2026

The local beaches in Puerto Rico and the US Virgin Islands will have a low risk of rip currents for the rest of the day. It's important to note that even at low-risk beaches, isolated, life- threatening rip currents can still occur, particularly near jetties, groins, reefs, and piers. Tomorrow, some beaches in southeastern and eastern Puerto Rico, as well as Vieques, Culebra, St. Croix, St. John, and St. Thomas, will face a moderate risk of life-threatening rip currents. This moderate risk is expected to extend to other beaches in northwest Puerto Rico on Sunday. It will continue to spread to additional beaches next week as winds increase and the frequency of breaking wave action intensifies.

Afternoon convection may bring one or two isolated thunderstorms to some areas in Puerto Rico through the evening. If you're outdoors, stay alert for lightning. Remember: if you hear thunder, move to a sturdy building or a hard-topped vehicle immediately and remain there for at least 30 minutes after the last thunder.

Expect hot and humid conditions that may create dangerous heat levels at the beaches. Stay hydrated, seek shade often, wear lightweight clothing, and limit prolonged sun exposure during the hottest parts of the day.

FIRE WEATHER

Issued at 200 PM AST Fri Jul 3 2026

Weather surface stations across southern Puerto Rico registered winds near or above the critical values, around 14 to 18 mph with gusts up to 20 to 28 mph. Minimum relative humidity values are in the mid 50 to low 60s, particularly across Guanica and Camp Santiago stations. Combined with dry fuels, the fire weather threat remains low. Winds are expected to become breezier in the coming days, fire weather partners are expected to remain vigilant, particularly across southern coastal plains of Puerto Rico.

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.