Hurricane Season runs from June 1-November 30
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Area Forecast Discussion (AFD)
091 FXCA62 TJSJ 120606 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 206 AM AST Fri Jun 12 2026 ...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST, FIRE WEATHER... .KEY MESSAGES... Issued at 148 AM AST Fri Jun 12 2026 * Expect showers and some isolated thunderstorms this afternoon across northwestern PR. There is limited flood risk for that area. * Hot heat index values will prevail from Friday onward, especially across urban, coastal, and lower-elevation areas. However, a Heat Advisory is not in effect as enough cloudiness continues to prevail across the islands. * Saharan dust particles will generate hazy skies, today. Trace concentrations are expected to persist through the weekend. * Increasing winds through the weekend will slightly deteriorate beach conditions. * A moderate risk of life-threatening rip currents will return tonight along north central PR and St. Croix, expanding to more areas from tonight onwards. && .Short Term(Today through Sunday)... Issued at 148 AM AST Fri Jun 12 2026 Overnight, mostly cloudy skies prevailed across the islands as moisture associated with a nearby trough and tropical wave lingered across the region. This maintained temperatures across urban and coastal areas in the upper 70s to low 80s, while mountainous areas remained in the low to mid 70s. Overall, the persistent cloud cover prevented the daytime heat from fully escaping overnight, resulting in warm and humid conditions across the islands. Today, weather conditions are expected to gradually improve as a drier air mass begins filtering into the region. The latest model guidance shows precipitable water (PWAT) and relative humidity values decreasing to below normal levels for this time of year, supporting a gradual transition toward a more stable weather pattern. At the same time, NASA Dust Aerosol Optical Thickness guidance continues to indicate low concentrations of Saharan dust moving across the islands, promoting hazy skies today through the weekend. People with respiratory conditions are urged to follow recommendations from health experts and limit prolonged outdoor exposure when possible. Even with the drier trend, daytime heating and local effects may still trigger isolated to locally scattered afternoon showers, mainly across northwestern Puerto Rico due to the continued southeasterly wind flow. Mid-level temperatures around -7 to -8 degrees Celsius may still support limited convective development before gradually warming from Saturday onward. Overall, today will serve as a transition day between the recent wetter pattern and a drier, more stable weekend. When talking about heat for today, we decided to hold off on issuing a Heat Advisory as enough cloud cover has remained across the area. However, we still anticipate periods where heat indices could briefly reach Heat Advisory criteria at times. Therefore, people without adequate hydration or cooling should remain aware and continue monitoring the latest forecasts. Through the weekend, conditions are expected to become more stable as a drier air mass dominates the region while low concentrations of suspended Saharan dust continue to promote hazy skies. The driest and more stable period of the short-term forecast is expected from Saturday into Sunday, when a more typical trade wind pattern establishes across the local islands. Under this pattern, brief passing showers will remain possible across windward areas during the morning hours, followed by isolated afternoon showers mainly across northwestern to western Puerto Rico. Winds are also expected to increase through the weekend, meaning that any showers that do develop will move quickly across the area, limiting the potential for significant rainfall accumulations. The main impacts through the weekend will continue to be the warm temperatures, hazy skies, and periods of uncomfortable heat, especially across coastal and urban areas where heat indices could reach or exceed advisory criteria. Residents are still encouraged to stay hydrated, take breaks from prolonged outdoor activity, and monitor the latest forecasts. && .Long Term(Monday through Friday)... Issued at 148 AM AST Fri Jun 12 2026 Some changes were introduced to the long-term forecast. As discussed in previous discussions, a surface high pressure building and lingering through most of the period, promoting E-ESE winds that will lead to breezy to locally windy conditions across the islands. Through Wednesday, drier air masses, along with minor concentrations of SAL, and patches of moisture embedded in the trades will likely move across the region, with PWAT values fluctuating mainly between 1.3 and 1.6 inches. Taking a look at the latest cross-section, the highest moisture content concentrates in the 1000 - 850 mb layer, while RH values drop to 10 - 30 % in the 700 - 500 mb layer. A mid- level ridge should linger through Wednesday, maintaining typical and slightly warmer than normal 500 mb temperatures (between -6 and -7 degrees Celsius), allowing subsidence and stability aloft. From Monday through early Thursday, isolated showers may move from time to time over windward sections, with shallow afternoon convection over portions of western/northwestern Puerto Rico. Since rainfall accumulations should remain limited, no flooding threat is expected. By late Thursday, the latest global solutions suggest an increase in moisture content, associated with a tropical wave that may move south of the CWA and a TUTT that could amplify and move closer to the region. While PWAT values should increase between 1.5 and 1.75 inches, the TUTT may cool mid-level temperatures, suppress high- level heights, and enhance vertical motion. These conditions should increase instability across the CWA, enhancing the potential of deep convection and lightning threat. Therefore, isolated to scattered showers and isolated thunderstorms may move over the windward sections by Thursday evening. Nevertheless, the highest flooding potential can be expected late Thursday night into Friday. Typical to warmer than normal conditions can be expected through the long-term, which may increase the chance of heat indices exceeding 100 degrees Fahrenheit. Hence, the heat threat will remain limited to elevated across urban and lower elevations of the islands. Heat Advisories will be issued if required. && .AVIATION... (06Z TAFS) Issued at 148 AM AST Fri Jun 12 2026 VFR conditions across all TAF sites. Low HZ due to Saharan dust will persist through the period, particularly aft 12/10Z with brief periods of reduced VIS possible. E-ESE winds will increase to 10-16 kt, with hir gusts and sea breeze variations aft 12/13Z. Winds will decrease to 5-10 kt after 12/23Z. && .MARINE... Issued at 148 AM AST Fri Jun 12 2026 Through at least tonight, up to moderate east to east-southeast winds and seas of 2 to 4 feet will prevail across the regional waters. However, a surface high over the Atlantic will continue to strengthen tomorrow, Saturday. This will support fresh trades and more choppy seas Saturday through at least next midweek. Seas are forecast to build to 4 to 6 feet, occasionally higher, across the regional waters and local passages. This will result in Small Craft Should Exercise Caution conditions. Patches of moisture and showers will continue over the area this morning, however drier air behind yesterday`s tropical wave along with Saharan Dust concentrations will promote more stable conditions. However, groups of showers will continue to be steered by the winds towards the local waters. && .BEACH FORECAST... Issued at 148 AM AST Fri Jun 12 2026 Gradually increasing winds will result in sectors under a moderate risk of rip currents (life-threatening rip currents are possible in the surf zone) today, mainly over beaches of north-central PR and St. Croix. For today, there will be a low risk of rip currents for most of the rest of the local beaches. However, life-threatening rip currents may still occur, especially near groins, jetties, reefs, and piers. The moderate risk of rip currents will then spread tonight to other north oriented beaches. Breezy to locally windy conditions will then result in a moderate risk of rip currents for most of the local beaches of Puerto Rico and the USVI, Saturday through at least the next midweek. Beachgoers should exercise caution, always swim near a lifeguard and remember to heed the advice of the local beach patrol and flag warning systems. Other hazards include limited to elevated heat risks, Saharan Dust concentrations filtering over the region and breezy E to ESE winds (unsecured items could blow around). && .FIRE WEATHER... Issued at 148 AM AST Fri Jun 12 2026 Today, expect a low fire weather risk across the southern sections of the islands. However, by Saturday, a dry air mass is expected to move over the forecast area, potentially lowering relative humidity values to near or below critical thresholds across the southern coastal plains, and possibly extending into other areas. Additionally, breezy conditions are expected to return on Saturday. Combined with above-critical KBDI values and increasingly dry fuels, this could lead to elevated fire danger conditions. Therefore, conditions may become favorable for the spread of wildfires along the southern coastal plains of Puerto Rico on Saturday, and a Fire Danger Statement (RFDSJU) may be necessary. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM/AVIATION...MMC LONG TERM...MNG MARINE/BEACH FORECAST...MRR FIRE WEATHER...CVB
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