Northwestern 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 With Gusts Up To 20 Knots Late This Evening And Overnight. Seas 2 To 3 Feet. Wave Detail: Northeast 2 Feet At 6 Seconds And South 1 Foot At 5 Seconds. Scattered Showers Early This Evening, Then Isolated Showers Late This Evening. |
| Monday...East Winds 5 To 10 Knots, Becoming Northeast In The Afternoon. Seas 2 To 3 Feet. Wave Detail: South 1 Foot At 5 Seconds. Numerous Showers In The Afternoon. |
| Monday Night...East Winds 5 To 10 Knots. Seas 2 To 3 Feet. Wave Detail: South 1 Foot At 4 Seconds And Northeast 1 Foot At 7 Seconds. Scattered Showers In The Evening. |
| Tuesday...East Winds 5 To 10 Knots, Diminishing To Around 5 Knots In The Afternoon. Seas Around 2 Feet. Wave Detail: South 1 Foot At 5 Seconds. Numerous Showers In The Afternoon. |
| Tuesday Night...East Winds Around 5 Knots, Increasing To 5 To 10 Knots After Midnight. Seas Around 2 Feet. Wave Detail: South 1 Foot At 5 Seconds. Scattered Showers In The Evening. |
| Wednesday...East Winds Around 5 Knots, Becoming Northeast 10 To 15 Knots With Gusts Up To 20 Knots In The Afternoon. Seas Around 2 Feet. Wave Detail: Northeast 1 Foot At 2 Seconds And South 1 Foot At 5 Seconds. Scattered Showers In The Afternoon. |
| Wednesday Night...Northeast Winds 10 To 15 Knots With Gusts Up To 25 Knots. Seas 2 To 3 Feet. |
| Thursday...East Winds 10 To 15 Knots. Seas 2 To 3 Feet. Scattered Showers In The Afternoon. |
| Thursday Night...East Winds 15 To 20 Knots, Diminishing To 10 To 15 Knots After Midnight. Seas 2 To 4 Feet, Occasionally To 5 Feet. |
| Friday...East Winds 5 To 10 Knots. Seas 2 To 3 Feet. Scattered Showers In The Afternoon. |
| Friday Night...East Winds 10 To 15 Knots. Seas 2 To 4 Feet, Occasionally To 5 Feet. |
| Area Forecast Discussion National Weather Service San Juan PR 259pm AST Sunday August 23 2026 .Short Term(This evening through Tuesday)... Issued at 259pm AST Sunday August 23 2026 During the morning hours, overall quiet conditions prevailed, with only minimal showers across the windward areas of Puerto Rico. Around midday, cloudiness increased, with USVI streamers reaching portions of eastern Puerto Rico, while showers across interior Puerto Rico began to develop. Daytime maximum temperatures ranged from the upper 80s to low 90s across coastal and urban areas and from the low 80s across higher-elevation areas. A Heat Advisory remains in effect until 4pm AST. Residents are encouraged to stay well hydrated, wear lightweight and loose- fitting clothing, take frequent breaks from the sun, and follow other heat-safety precautions. The overall wind flow will remain moderate easterly across the region, associated with a surface high pressure system over the Atlantic. For the rest of the afternoon, convection and isolated thunderstorms across western sections, driven by local effects, are ongoing and are expected to continue through sunset. This activity is associated with a weak tropical wave moving across the islands, which is causing precipitable water values to increase toward seasonal averages of around 1.75 to 1.9 inches. During the overnight period, wind-driven showers are forecast across the USVI and the windward sectors of Puerto Rico. By Monday, a seasonal pattern is expected as the tropical wave moves away. Nevertheless, limited afternoon convection and an elevated heat threat will remain. Global model guidance continues to suggest an increase in the frequency of showers and afternoon convection as another tropical wave arrives in the region, with precipitable water values reaching up to 2 inches based on guidance. As a result, a more active shower and thunderstorm pattern is expected throughout Tuesday, particularly where local and diurnal effects enhance convection. For the remainder of the short-term period, an elevated to significant heat threat is forecast to prevail, particularly across coastal and urban areas of the islands. Additional heat product alerts will likely be needed in the coming days. .Long Term(Wednesday through Sunday)... Issued at 335am AST Sunday August 23 2026 During the long-term period, the weather pattern will be mainly dominated by high pressure across the central Atlantic and the passage of tropical waves, primarily from the east to southeast. Aloft, a mid-level ridge will dominate for most of the period. By Wednesday, remnant moisture associated with a tropical wave will remain across the region. Current guidance indicates that precipitable water values will remain near seasonal levels; however, moderate to locally high concentrations of Saharan dust will persist across the region before decreasing Wednesday night into Thursday. As a result, mainly fair weather, hazy skies, and hot temperatures are expected across the U.S. Virgin Islands. Across Puerto Rico, expect passing morning showers over windward areas, with limited afternoon convection across western municipalities. By Thursday, overall drier air will dominate, with PWAT (Precipitable Water) values falling below seasonal averages. However, intermittent patches of moisture will continue to move across the region. An upper-level trough will linger, resulting in cooler 500-mb temperatures, while the mid-level ridge will still provide some stability. Despite this, diurnal heating and local effects will support the development of afternoon convection, including isolated thunderstorms across western Puerto Rico, which could result in a limited flood threat. From Friday into Saturday, current model guidance suggests the arrival of a tropical wave, increasing tropical moisture up to 2.25 inches. Uncertainty remains in the forecast during this period, so residents and interests across the region are encouraged to continue monitoring the latest forecasts and the evolution of the tropical wave. By Sunday, precipitable water values are expected to decrease to seasonal or below-normal levels, limiting rainfall chances. One persistent hazard throughout the period will be excessive heat, with an elevated heat threat expected on most days. Wednesday could pose a particularly significant heat threat due to above-normal 925- mb temperatures, southeasterly winds, the presence of Saharan dust, and seasonal moisture levels. Residents are encouraged to stay well hydrated, wear lightweight and loose-fitting clothing, take frequent breaks from the sun, and follow other heat-safety precautions. Marine Issued at 259pm AST Sunday August 23 2026 No changes were introduced to the marine forecast. Recent scatterometer data shows moderate trade winds across the regional waters and passages, while the latest altimeter scan reported seas between 2 and 4 feet, with isolated areas at 5 feet. This pattern should continue through midweek as the surface high pressure builds over the central Atlantic. A weak tropical wave approaching the Caribbean basin should increase the frequency of showers across the local Caribbean waters and passages this afternoon into the evening. Afterward, another tropical wave is forecast to approach the eastern Caribbean around Tuesday, bringing enhanced shower and thunderstorm activity once again. As winds gradually increase by midweek and become moderate to locally fresh, seas should build to 3-5 feet, occasionally 6 feet, across offshore waters and passages; small craft must exercise caution. Beach Forecast Issued at 259pm AST Sunday August 23 2026 Beach conditions remain tranquil for beachgoers, as the low risk of rip currents continues across the islands. The nearshore buoys show seas between 1 and 3 feet, with winds between 10 and 15 kt, occasionally up to 20 kt. These conditions should continue for the first part of the week, though beachgoers must exercise caution, as life-threatening rip currents can often occur in the vicinity of jetties, reefs, groins, and piers. By Wednesday into Thursday, a gradual increase in winds and seas will likely upgrade the risk to moderate, particularly across northern and eastern-exposed beaches of the islands, increasing the likelihood of rip currents along the surf zone. The moderate risk should continue throughout the end of the week. As mentioned in the previous discussion, showers and isolated thunderstorms can be expected each afternoon, moving across western coastal areas of Puerto Rico. Beachgoers should remain weather alert, as isolated thunderstorms could produce gusty winds and lightning. Fire Weather Issued at 259pm AST Sunday August 23 2026 During the morning hours, moisture content is associated with a tropical wave approaching the region. RAWs/AWOS stations across the southern coastal plains of Puerto Rico and St. Croix in the U.S. Virgin Islands reported winds between 20 - 23 mph, with gusts up to 31 mph. Although stations reported a gradual decrease in RH values and the Guanica station reached threshold values, it was brief. Given the current conditions and the forecast, the risk will remain low for the rest of today, though residents and visitors are encouraged to avoid outdoor burning, as critical dry fuels and drought conditions continue and could increase the likelihood of wildfire ignition and rapid spread. .SJU WATCHES/WARNINGS/ADVISORIES... PR... Heat Advisory until 4pm AST this afternoon for PRZ001>003-005- 007-008-010>013. VI... Heat Advisory until 4pm AST this afternoon for VIZ001-002. AM...None. |
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