Northern Puerto Rico out 10NM Marine Forecast
| Tonight...East Winds 10 To 15 Knots With Gusts Up To 20 Knots, Diminishing To 5 To 10 Knots Late This Evening And Overnight. Seas 2 To 3 Feet. Wave Detail: Northeast 3 Feet At 8 Seconds. Isolated Showers This Evening. Scattered Showers After Midnight, Then Isolated Showers Late. |
| Saturday...East Winds 10 To 15 Knots, Increasing To 15 To 20 Knots With Gusts Up To 25 Knots In The Afternoon. Seas 3 To 4 Feet, Occasionally To 5 Feet. Wave Detail: Northeast 3 Feet At 8 Seconds. |
| Saturday Night...East Winds 10 To 15 Knots With Gusts Up To 25 Knots, Becoming Southeast 5 To 10 Knots After Midnight. Seas 3 To 4 Feet, Occasionally To 5 Feet. Wave Detail: East 3 Feet At 8 Seconds. |
| Sunday...East Winds 5 To 10 Knots, Increasing To 10 To 15 Knots With Gusts Up To 25 Knots In The Afternoon. Seas Around 3 Feet. Wave Detail: East 3 Feet At 7 Seconds. Scattered Showers In The Morning, Then Numerous Showers In The Afternoon. |
| Sunday Night...East Winds 10 To 15 Knots With Gusts Up To 20 Knots, Becoming Southeast 5 To 10 Knots After Midnight. Seas Around 3 Feet. Wave Detail: East 3 Feet At 7 Seconds. Scattered Showers. |
| Monday...East Winds 10 To 15 Knots, Increasing To 15 To 20 Knots In The Afternoon. Seas 3 To 4 Feet, Occasionally To 5 Feet. Wave Detail: East 3 Feet At 7 Seconds And North 1 Foot At 10 Seconds. Numerous Showers In The Afternoon. |
| Monday Night...East Winds 10 To 15 Knots With Gusts Up To 20 Knots. Seas 3 To 4 Feet, Occasionally To 5 Feet. |
| Tuesday...East Winds 10 To 15 Knots, Increasing To 15 To 20 Knots In The Afternoon. Seas 3 To 4 Feet, Occasionally To 5 Feet. Scattered Showers In The Afternoon. |
| Tuesday Night...East Winds 10 To 15 Knots. Seas 4 To 5 Feet, Occasionally To 6 Feet. |
| Wednesday...East Winds 10 To 15 Knots, Increasing To 15 To 20 Knots In The Afternoon. Seas 4 To 5 Feet, Occasionally To 6 Feet. Scattered Showers. |
| Wednesday Night...East Winds 10 To 15 Knots. Seas 4 To 5 Feet, Occasionally To 6 Feet. |
| Area Forecast Discussion National Weather Service San Juan PR 200pm AST Fri September 4 2026 .KEY MESSAGES... Issued at 135pm AST Fri September 4 2026 * Higher moisture content is expected through Monday, resulting in more frequent showers and thunderstorm development, particularly during the afternoons across the western interior and northern portions of PR. Locally heavy rainfall could result in urban and small stream flooding, as well as ponding of water on roads and in poor drainage areas. * Dangerous heat conditions will continue through the weekend across all islands. A Heat Advisory is in effect through at least 5pm this afternoon, while even warmer and more humid conditions could result in significant heat impacts this weekend, particularly on Sunday. * For the USVI, showers with brief periods of moderate to heavy rains are expected each afternoon through at least Monday. * A low risk of rip currents will prevail across all beaches through the Holiday weekend. However, life-threatening rip currents can still occur when the risk is low, particularly near groins, jetties, reefs, and piers. .Short Term(This evening through Sunday)... Issued at 135pm AST Fri September 4 2026 Calm conditions prevail over the forecast region. Passing showers developed over the windward waters during the morning hours with minimal rainfall accumulation. High humidity over the region associated with a weak tropical wave coupled with daytime heating and local effects may favor the development of afternoon showers and thunderstorms along the interior and western portions of Puerto Rico after 3PM. Nonetheless, their effects will remain limited due to mid-level stability. Rip current risk remains low but caution should still be exercised when swimming at the beach as the development of life threatening isolated events cannot be ruled out. Overall, the main threat for today into the weekend will be the elevated heat risk. Thus, a heat advisory remains in effect until 5pm today. Deeper moisture will continue to promote a wetter pattern over the weekend. The next tropical wave is expected to arrive on Sunday, bringing additional moisture into the islands. Model guidance continue to suggests precipitable water values increasing up to 2 inches or above normal values for time of the year and relative humidity at the mid levels (700mb-500mb) staying above normal values across Puerto Rico and the US Virgin Islands, through the beginning of the workweek. This will support the development of locally heavy rainfall and thunderstorms during the afternoons, combined with the local effects and diurnal heating. The flood threat for the weekend will gradually become elevated Saturday into Sunday, with more areas under this threat on Sunday. Heat risks will remain as one of the main hazards over the next few days. Warmer temperatures, combined with a southeasterly flow dragging warm air into the local area, will promote and increase in heat indices. On Sunday, expect above normal 925-mb temperatures and abundant moisture, increasing the potential of Extreme Heat Risk. Nevertheless, cloud coverage associated with the incoming tropical wave can limit daytime heating. Regardless, we encourage citizens and visitors to continue monitoring the forecast as mostly variable condition will prevail. .Long Term(Monday through next Thursday)... Issued at 135pm AST Fri September 4 2026 Some changes were made to the long-term forecast, as conditions are likely to be variable across the CWA. As mentioned in the previous surface high pressure will dominate the wind pattern, promoting an easterly-southeasterly flow and leading to breezy to locally windy conditions by mid next week. Under these conditions, any showers will become progressive rather than stationary. A tropical wave is still forecast to move across the islands by Tuesday, though the NASA GMAO Dust Extinction AOT suggests concentrations of Saharan Dust surrounding the wave, which may weaken it by the time it approaches the local area. From the latest model guidance, solutions show the most active area north of the CWA, though moisture content should remain seasonal to well above- climatological normal (PWATs (Precipitable Waters) between 1.9 - 2.1 inches) with the main bulk of moisture in the low and mid levels (RHs above 60 percentage). Although the most likely scenario is to observe shower activity moving over windward sections in the morning and afternoon convection, the presence of a mid to high level ridge may limit thunderstorm activity in the afternoon, though Saharan Dust concentrations may boost the lightning activity. Rainfall accumulations across interior and northwestern Puerto Rico could lead to ponding of water over roadways and poorly drained areas, along with minor flooding. As moisture content reduces and drier air filters into the mid levels, the weather pattern on Wednesday may be less convective, driven mainly by daytime heating and local effects, posing no flooding threat. A tropical wave is forecast to move near the CWA (County Warning Area) by late Thursday into Friday, pooling tropical moisture (PWATs (Precipitable Waters) once again between 1.9 - 2.2 inches), mainly over the eastern side of Puerto Rico. The most likely scenario is an advective pattern across windward sections of the islands early Friday, with afternoon convection if cloud cover allows it. These accumulations could enhance the flooding threat, particularly across the eastern side of Puerto Rico and the U.S. Virgin Islands, with the highest threat across northwestern Puerto Rico. The drier conditions mentioned in the previous conditions may be delayed, as guidance suggests the arrival of drier air by the end of the period. Warmer to hot conditions are still on forecast, with Monday and Tuesday likely to the warmest days of the long-term period. Marine Issued at 135pm AST Fri September 4 2026 Light to moderate east to southeast winds will prevail through at least Monday. Winds will strengthen and become moderate to fresh from Tuesday onward as surface high pressure builds across the central Atlantic, resulting in increasingly choppy seas. Moisture behind a weak tropical wave will bring scattered showers and isolated thunderstorms on Saturday. Another tropical wave will increase shower and thunderstorm activity from Sunday into Monday. Beach Forecast Issued at 135pm AST Fri September 4 2026 A low risk of rip currents is expected across all beaches of Puerto Rico and the US Virgin Islands through the Holiday weekend. However, dangerous rip currents can still occur near groins, jetties, reefs, and piers. Beachgoers should enjoy the favorable conditions while being mindful of isolated rip currents and changing weather. Afternoon thunderstorms with cloud-to-ground lightning are expected across most islands during the weekend. A moderate risk of rip currents is expected through much of the workweek as winds and seas increase across the coastal waters of the islands. .SJU WATCHES/WARNINGS/ADVISORIES... PR... Heat Advisory until 5pm AST this afternoon for PRZ001>013. VI... Heat Advisory until 5pm AST this afternoon for VIZ001-002. AM...None. |
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