textproduct: San Juan

KEY MESSAGES

Issued at 142 PM AST Tue Jun 23 2026

* A small area of cloudiness and showers will move during the rest of the afternoon hours, resulting in some showers along eastern sections of Puerto Rico with minimal rainfall accumulations.

* There is a low to moderate risk of rip current across all the coastal areas tonight.

* Another pulse with moderate concentrations of Saharan Dust is forecast to arrive at the local islands by late Wednesday into Thursday.

* The moisture field from a weak tropical wave moving across the region by Wednesday will enhance the potential for some localized showers tomorrow across western interior Puerto Rico.

Short Term(This evening through Thursday)

Issued at 142 PM AST Tue Jun 23 2026

Very calm weather conditions prevailed during the morning hours across Puerto Rico and the U.S. Virgin Islands under mostly clear and sunny skies. By early afternoon, a band of clouds and showers ahead of an approaching tropical wave began to move across the U.S. Virgin Islands, leaving minor accumulations over St. Thomas, St. John, and portions of St. Croix. However, the rest of the area remained relatively calm. It was another day with maximum temperatures reaching the upper 80s to low 90s across the lower elevations, and the low to mid-80s in the higher mountains. By noon, the temperature at the Luis Munoz Marin International Airport in San Juan hit 89F. Winds blew from the east at 15 to 20 mph, with higher gusts and local sea breeze variations.

The band of showers and clouds will continue to move westward toward eastern Puerto Rico, Vieques, and Culebra, potentially bringing rounds of showers to these areas this afternoon. Later in the day, this moisture will combine with daytime heating and local effects to trigger localized showers and a few isolated thunderstorms over western Puerto Rico. The latest model guidance suggests minimal accumulations across these sectors. By Wednesday, the tropical wave will continue to approach the region; however, the bulk of the moisture is expected to remain south of the area over the Caribbean Sea, the ABC islands, and Venezuela. Nonetheless, its northern periphery will reach the northeastern Caribbean, pushing precipitable water values (PWAT) up to 1.75 inches. Given this moisture, similar weather conditions are anticipated: passing showers will move across eastern Puerto Rico and the U.S. Virgin Islands, followed by afternoon convection across western Puerto Rico. At this time, the expected shower activity will remain localized with limited impacts across the area, though ponding of water and minor flooding remain possible.

By Wednesday evening and into Thursday, a drier airmass will follow the tropical wave, bringing moderate to high concentrations of Saharan Dust. This pattern will result in hazy skies, reduced visibility, and poor air quality. Sensitive groups, particularly individuals with respiratory conditions, should take the necessary precautions to limit outdoor exposure and follow medical guidance. This dust event is expected to continue through the rest of the week. Meanwhile, above-average seasonal temperatures will persist through the weekend, with maximum temperatures ranging from the upper 80s to low 90s along coastal and urban areas, and from the upper 70s to low 80s in the higher elevations.

Long Term(Friday through next Monday)

Issued at 346 AM AST Tue Jun 23 2026

Variable conditions will prevail in the long-term forecast, with the highest flood potential on Saturday. The broad surface high pressure over the Central Atlantic may weaken as an upper-level low northeast of the CWA induces a surface trough, reducing the local pressure gradient and causing winds to become light from the northeast through Saturday. Due to lingering moderate to high concentrations of SAL over the region and PWAT values below climatological normal (1.4 and 1.6 inches), weather activity should remain limited on Friday, with shallow afternoon convection over the western/southwestern portion of Puerto Rico. From the latest model guidance, PWAT values may increase to seasonal values (1.6 and 1.8 inches), as the induced trough approaches the local area. Taking a look at the latest model cross-section, theres a rise in the 850- 700 mb RH, though the 700 - 500 mb layer remains dry. Additionally, the latest model solution shows warmer-than-normal temperatures (500 mb temperatures above -6 degrees Celsius), while the Galvez-Davison Index (GDI) suggests the potential of isolated thunderstorms. Although these conditions arent optimal for deep convection and the trough should remain north of the CWA, the combination of local effects, daytime heating, available moisture, and weak winds could bring afternoon showers and isolated thunderstorms over the western side of Puerto Rico. Rainfall accumulations may lead to ponding of water over roadways, urban, and poorly drained areas, including minor flooding. As the induced trough migrates northwestward and winds strengthen from the southeast, a drier air mass should filter into the region on Sunday, limiting once again shower activity. However, a tropical wave may approach the Caribbean Basin and increase low-level moisture content across the local islands, though theres uncertainty introduced to the forecast as low to moderate concentrations of Saharan Dust may weaken it and limit shower activity.

Under a southeasterly, Sunday may be the hottest day of the period, with warmer-than-normal 925 mb temperatures and available moisture that could make heat indices exceed 100 degrees Fahrenheit and pose a threat. Hence, a Heat Advisory may be issued if required.

AVIATION

(18Z TAFS) Issued at 142 PM AST Tue Jun 23 2026

VFR conditions are forecast across all TAF sites. Winds will remain form the E-ENE at 18 knots or less, diminishing at 23/23Z and becoming more variables up to 10 knots and increasing again by 24/15Z. VCSH to SHRA are expected across TIST and TJSJ until 23/23Z. HZ is forecast again by late Wednesday afternoon across TIST and TISX.

MARINE

Issued at 142 PM AST Tue Jun 23 2026

No changes to the inherited forecast. At the surface, a broad surface high-pressure system over the central Atlantic will maintain moderate to fresh easterly to east-northeast winds during the day, resulting in choppy seas across most of the local waters. Therefore, small craft should exercise caution. A tropical wave arriving at the local islands by Wednesday is forecast to produce brief, strong showers over the local Caribbean waters, leading to localized hazardous marine conditions. Another pulse of moderate concentrations of Saharan Dust will return late tonight, while high concentrations arrive by late Wednesday night into early Thursday and persist through Friday.

BEACH FORECAST

Issued at 142 PM AST Tue Jun 23 2026

For tonight, there is a low to moderate risk of rip currents along all the coastal areas. A few patches of cloudiness and showers are forecast along eastern sections of Puerto Rico in the early evening hours, resulting in some brief showers, but not significant rainfall accumulations. The risk of rip currents will remain moderate for the rest of the workweek into the upcoming week along all coastal areas. However, beachgoers are urged to exercise caution in some dangerous areas along the north-coastal areas of Puerto Rico.

SJU WATCHES/WARNINGS/ADVISORIES

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