Issued by: National Weather Service San Juan, PR
Updated: 4:06 pm AST Jun 23, 2025
| Overnight | Isolated showers. Partly cloudy, with a low around 78. East southeast wind around 10 mph. Chance of precipitation is 20%. |
| Tuesday | Scattered showers, mainly after 3pm. Widespread haze between noon and 3pm. Mostly sunny, with a high near 90. Heat index values as high as 102. East wind 11 to 18 mph, with gusts as high as 24 mph. Chance of precipitation is 50%. |
| Tuesday Night | Isolated showers after midnight. Widespread haze before 9pm. Partly cloudy, with a low around 78. East wind 11 to 13 mph. Chance of precipitation is 20%. |
| Wednesday | Isolated showers before noon. Sunny, with a high near 90. East wind 14 to 20 mph. Chance of precipitation is 10%. |
| Wednesday Night | Widespread haze. Clear, with a low around 78. East wind 9 to 11 mph. |
| Thursday | Isolated showers before noon. Widespread haze. Sunny, with a high near 89. East wind 11 to 17 mph, with gusts as high as 23 mph. Chance of precipitation is 10%. |
| Thursday Night | Widespread haze. Partly cloudy, with a low around 77. East wind 9 to 11 mph. |
| Friday | Mostly sunny, with a high near 89. East northeast wind 9 to 14 mph. |
| Friday Night | Partly cloudy, with a low around 76. East wind around 9 mph. |
| Saturday | Sunny, with a high near 89. |
| Saturday Night | Mostly clear, with a low around 77. |
| Sunday | Scattered showers. Mostly sunny, with a high near 90. Chance of precipitation is 30%. |
| Sunday Night | Partly cloudy, with a low around 78. |
| Monday | Sunny, with a high near 90. |
042 FXCA62 TJSJ 231857 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 257 PM AST Mon Jun 23 2025 .KEY MESSAGES... * A tropical wave moving away south of the region will maintain shower and thunderstorm activity tonight, gradually improving into tomorrow. * Moderate concentrations of Saharan Dust are expected mainly tomorrow and Thursday, with a slightly decrease in concentrations during Wednesday. Hazy skies and poor air quality are expected. * Daily afternoon showers and isolated thunderstorms are expected, particularly over western Puerto Rico due to local effects. * By the end of the week into the weekend, a TUTT-low is forecast to develop just north/northeast of the region, and another tropical wave is expected to enter the eastern Caribbean. && .SHORT TERM...Tonight through Wednesday... Variable weather conditions under partly to mostly cloudy skies prevailed across the forecast area this morning, influenced by a tropical wave that has entered the eastern Caribbean, with its axis moving south of the islands. Due to this tropical wave, the latest model guidance suggests above-normal PWAT values exceeding 1.65 inches, and locally reaching up to 2.00 inches. Passing showers affected the eastern half of Puerto Rico earlier in the day. By midday, stronger showers developed, mainly over the northwestern quadrant of the island. Radar estimates indicated maximum rainfall accumulations of about 1 to 1.3 inches in Moca and along the coast of Aguada. These showers dissipated before 2 PM AST. In terms of winds, breezy to locally windy conditions persisted, with weather stations reporting gusts up to 30 mph at San Juan International Airport, Cabo Rojo, and St. Croix; 31 mph in St. Thomas; and 33 mph at Ponces Mercedita Airport, among other locations. For the remainder of the afternoon, some showers are expected to continue across western sectors of Puerto Rico. Tonight, models suggest the arrival of additional showers across eastern Puerto Rico, Vieques, and Culebra, with rain chances ranging from 30 to 60 percent in those areas, and 10 to 20 percent elsewhere. By Tuesday and Wednesday, following the passage of the tropical wave, drier air will filter into the region. This will lead to fewer and more localized afternoon showers and isolated thunderstorms, mainly driven by local effects. The flood threat will remain from none to limited, primarily for western Puerto Rico. A key topic for tomorrow will be the arrival of a moderate Saharan Air Layer. As a result, hazy skies, reduced visibilities, and poor air quality are likely. Normal to above-normal temperatures will also continue over the next several days, with 925 mb temperatures reaching the upper 80s to lower 90s in coastal and urban areas, and the upper 70s to low 80s in higher elevations. Fewer clouds and limited rain will contribute to an elevated heat risk. Please stay alert for any forecast updates and the possible issuance of a Heat Advisoryespecially for heat- sensitive individuals, including those without adequate cooling or hydration. By Wednesday, rainfall is expected to remain limited. Although Saharan dust concentrations will slightly decrease, hazy skies and warm temperatures will persist. .LONG TERM...Thursday through Monday... .PREV DISCUSSION... /issued 449 AM AST Mon Jun 23 2025/ A broad surface high pressure extending from the central Atlantic and a strong 850-700mb ridge moving just north of the region will continue to promote breezy conditions and drier air intrusion through early Friday. A weak Saharan Air Layer is expected to linger through Thursday over the region, promoting hazy skies. Fair weather conditions are expected in general across the islands on Thursday, with the exception of afternoon showers and isolated thunderstorms developing over western Puerto Rico due to diurnal and local effects. By late Friday into Saturday, a TUTT- low is forecast to develop just north/northeast of the region. An induced surface trough is expected to cross the region during this period, and winds will shift from the ENE, promoting afternoon shower development mainly over the SW quadrant of Puerto Rico. Across the the U.S. Virgin Islands and eastern Puerto Rico, showers are expected to increase mainly during the night. Lingering moisture on Saturday and ESE winds behind the trough passage will aid in the development of afternoon showers and thunderstorms once again over the NW quadrant of PR, and downwind from el Yunque. A tropical wave is expected to follow quickly and enter the eastern Caribbean between late Saturday and Sunday morning. Increasing the areal coverage of showers and thunderstorms once again across portions of the islands and local waters. && .AVIATION... (18Z TAFs) VFR conditions are mainly expected during this forecast period. VCSH are expected across TJSJ and USVI TAF sites tonight and during the morning hours. Tomorrow, VCTS are possible after 24/17Z across TJBQ with possible brief MVFR conditions. The main aviation concern tomorrow onward will be the arrival of a Saharan Air Layer, as a result reduced visibilities are likely over the next few days. && .MARINE... A subtropical Atlantic ridge extending southward into the northern Caribbean continues to promote moderate to locally fresh easterly winds, resulting in choppy seas across portions of the local Atlantic and Caribbean waters, as well as the local passages. Therefore, small craft should exercise caution across most waters. A tropical wave moving across the Caribbean Sea will continue to produce isolated to scattered showers and thunderstorms over the local waters tonight, with conditions gradually improving into tomorrow. && .BEACH FORECAST... Wave heights of around 3 to 4 feet and a moderate risk of rip currents are expected tonight along most beaches of Puerto Rico, including Vieques, Culebra, and the U.S. Virgin Islands. A moderate risk indicates that life-threatening rip currents are possible in the surf zone. As a result, beachgoers are encouraged to exercise caution, especially during the upcoming festivities. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM/AVIATION...YZR/MRR LONG TERM...DS
