textproduct: San Juan

KEY MESSAGES

Issued at 214 PM AST Sat Jun 20 2026

* Moderate to high concentrations of Saharan Dust will continue to filter into the region for the rest of the holiday weekend and early next week, resulting in hazy skies, reduced visibility, and poor air quality. Sensitive individuals should follow medical recommendations.

* Shower and thunderstorm activity on Fathers Day may result in ponding of water over roadways and minor flooding over portions of the U.S. Virgin Islands and Puerto Rico.

* Seasonal to warmer conditions will continue this holiday weekend and early next week, with heat indices ranging from the mid 90s and mid-100s across urban and low-lying areas of Puerto Rico and the U.S. Virgin Islands.

Short Term(This evening through Monday)

Issued at 214 PM AST Sat Jun 20 2026

Hazy, warm conditions prevailed once again across Puerto Rico and the U.S. Virgin Islands. The morning started calm under mostly sunny to partly cloudy skies, with no shower activity reported across the region. Maximum temperatures reached 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. Heat indices across the region surpassed 100F, particularly along the lower elevations of the islands where a Heat Advisory remains in effect until 5 PM AST. Winds blew from the east at 15 to 20 mph, with higher gusts and local sea breeze variations.

Moderate to high concentrations of Saharan dust will continue to reach the islands through the rest of the weekend, causing hazy skies, reduced visibility, and poor air quality. Sensitive groups, particularly individuals with respiratory conditions, should take necessary precautions to limit outdoor exposure and follow medical guidance.

A strong high-pressure system over the central Atlantic will continue to tighten the local pressure gradient, resulting in breezy east-east southeast winds through the end of the period. At the mid- levels, a ridge will maintain stable and drier conditions aloft. Meanwhile, an upper-level low located northeast of the Caribbean will continue to migrate northward, lifting its influence away from the region.

Despite this stable atmospheric setup, a tropical wave is expected to reach the islands by Sunday (Father's Day), increasing moisture and the potential for rain. The latest model guidance suggests precipitable water values (PWAT) will rise to between 1.75 and 1.90 inches. As this tropical wave passes, brief showers are expected across portions of eastern Puerto Rico and the USVI, followed by afternoon convection across western Puerto Rico driven by daytime heating and local effects. Any rainfall would be highly beneficial for areas currently experiencing abnormally dry or moderate drought conditions. However, forecast confidence remains low to moderate, as the wave is tightly embedded between layers of Saharan dust.

Long Term(Tuesday through next Friday)

Issued at 214 PM AST Sat Jun 20 2026

The long-term pattern aligns towards a typical June weather conditions. Moisture content, relative humidity values, and mid- level temperatures are forecast to remain near normal values for this time of the year, supporting a fairly typical trade-wind pattern across the islands.

On Tuesday, a relatively stable air mass will prevail across the region. Passing trade-wind showers will continue to affect windward and eastern sections of the islands, while leeward areas experience mostly fair weather. Temperatures will remain seasonably warm, with highs in the upper 80s to low 90s across coastal and urban areas.

A tropical wave is forecast to move across the region on Wednesday and Thursday. While the wave will bring an increase in low-level moisture and result in a higher frequency of passing showers, model guidance suggests precipitable water values will remain near seasonal values. In addition, mid-level relative humidity values remain relatively low and temperatures near 500 mb stay close to normals, limiting the potential for widespread deep convection. As a result, periods of passing showers are expected, particularly across windward and eastern sections in the morning as well as the afternoon convection across western PR, but significant rainfall accumulations are not anticipated at this time.

By late Thursday and continuing through Saturday, a slightly drier air mass will filter into the region. This will promote a decrease in shower coverage and support a return to a more typical trade-wind weather pattern. Although isolated showers will remain possible across windward areas, mostly fair weather conditions are expected elsewhere. Temperatures will continue near seasonal normals, and no significant weather impacts are anticipated through the end of the forecast period.

AVIATION

(18Z TAFS) Issued at 214 PM AST Sat Jun 20 2026

VFR conditions are expected to prevail across all terminals during the next 24 hours across all terminals. A dense plume of Saharan dust will continue to lower VIS across portions of the local flying area. HZ with VSBY dropping to near 6 SM will continue through the next few days. SHRA will form along the Cordillera and W-PR thru 20/23Z. E-ESE winds at 12-20 kt with sea breeze variations and stronger gusts thru 20/22Z-20/23Z. Winds will be calm to light and variable overnight thru 21/14Z.

MARINE

Issued at 214 PM AST Sat Jun 20 2026

A broad surface high pressure over the Central Atlantic will promote moderate to locally fresh easterly to east-southeasterly winds over the next several days. As the high strengthens and winds continue to strengthen, these conditions will lead to choppy seas across local waters and Caribbean passages; small craft should exercise caution. Low to moderate concentrations of Saharan Dust will persist throughout the weekend and mid-workweek, resulting in hazy skies, reduced visibility, and poor air quality. A tropical wave will move across the Caribbean Basin on Sunday into Monday, increasing the likelihood of showers and isolated thunderstorms across the local Caribbean waters and passages.

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.