Leeward Islands Offshore Forecast
| Today...E To Se Winds 10 Kt. Seas 3 To 5 Ft. |
| Tonight...E Winds 10 Kt. Seas 3 To 5 Ft. |
| Sun...E To Se Winds 10 Kt. Seas 2 To 4 Ft. |
| Sun Night...E Winds 10 Kt. Seas 2 To 4 Ft. |
| Mon...E Winds 10 Kt. Seas 2 To 4 Ft. |
| Mon Night...E Winds 10 Kt. Seas 2 To 4 Ft. |
| Tue...E To Se Winds 10 Kt. Seas 3 To 5 Ft. |
| Tue Night...E To Se Winds 10 Kt. Seas 3 To 5 Ft. |
| Wed...E To Se Winds 10 Kt. Seas 3 To 5 Ft. |
| Wed Night...E To Se Winds 10 Kt. Seas 2 To 4 Ft. |
| Area Forecast Discussion National Weather Service San Juan PR 310am AST Sat Oct 17 2026 .Short Term(Today through Monday)... Issued at 306am AST Sat Oct 17 2026 Variable weather conditions persisted overnight into the early morning hours across Puerto Rico and the U.S. Virgin Islands. Brief passing showers moved across the local Atlantic waters, occasionally reaching southeastern coastal sections of Puerto Rico. Rainfall accumulations remained minimal, as this activity was generally light and short-lived. Elsewhere, mainly fair weather prevailed with patches of cloudiness moving across the area. Overnight temperatures remained near seasonal values across the local islands, according to unofficial weather stations. A more variable weather pattern is expected today across the local islands as low-level moisture increases across the region. Recent satellite-derived estimates suggest precipitable water values have increased to around 1.69 inches as patches of moisture move across the area. At the surface, high pressure over the western Atlantic and a stationary front will influence the local wind pattern, maintaining easterly winds during the morning hours. These winds will gradually veer to the southeast by around 18Z, favoring somewhat warmer conditions, particularly across northern Puerto Rico. Under this pattern, afternoon showers are forecast across northwestern Puerto Rico and the San Juan metro area. However, a mid- to upper-level ridge will promote stable conditions across the region, limiting the vertical development of shower activity. Available moisture, combined with daytime heating and local effects, should still support afternoon showers across portions of the interior and northwestern Puerto Rico, where a limited flood threat is forecast. Similar conditions are forecast on Sunday, with southeasterly winds continuing to transport patches of low-level moisture across Puerto Rico and the U.S. Virgin Islands. Relative humidity at 850 mb is expected to fluctuate between 50 and 70 percent, suggesting intermittent moisture availability rather than a persistently moist air mass. This pattern will favor occasional passing showers across windward coastal areas, followed by locally induced afternoon activity over portions of the interior and northwestern Puerto Rico. The mid- to upper-level ridge will remain in place through Monday, maintaining a generally unfavorable environment for widespread deep convection. Rainfall should remain localized, although brief ponding of water may occur with heavier showers. Southeasterly flow will also maintain warm daytime conditions, especially across the northern coastal and urban areas of Puerto Rico. This level of heat will primarily affect individuals who are extremely sensitive to heat, especially when outdoors without effective cooling or adequate hydration. .Long Term(Tuesday through Saturday)... Issued at 306am AST Sat Oct 17 2026 A similar weather pattern will be observed throughout the long-term forecast with convective activity being predominantly driven by diurnal heating and local effects. As the mid- to upper-level trough moves further into the east Atlantic, a mid-level ridge will begin its gradual development over the region. This will maintain warmer than average temperatures at these levels and weaken the lapse rates into mid-week, thus inhibiting the development of deep convective cells. A surface ridge will also build from Tuesday into Wednesday weakening the pressure gradient and winds at these levels until Friday when locally breezy conditions return to the area. This feature will also steer the flow to be from E on Tuesday to SE for the remainder of the long-term forecast. The models show a predominantly moist column, particularly by late week. Given that the synoptic conditions will be acting to limit the development of convection, any activity that does develop will be driven by diurnal heating, available moisture, and local effects. Thus, the potential for excessive rainfall- and lighting- associated risks will increase as the week progresses. The focus of the activity will be predominantly the western interior and northwest of Puerto Rico during the afternoons with the exception of Wednesday which should favor the northern half of Puerto Rico during the afternoon. This level of risk may lead to flooding in urban areas, roads, small streams, and washes as well as to a low chance of isolated flash floods. The available moisture, above average low tropospheric temperatures, and low surface winds will lead to a level of heat that may affect those individuals extremely sensitive to heat especially when outdoors without effective cooling and/or adequate hydration. Individuals are invited to continue monitoring Marine Issued at 306am AST Sat Oct 17 2026 Gentle to moderate easterly winds will gradually shift to the east- southeast this weekend. A building upper-level ridge will limit widespread shower and thunderstorm activity, although occasional passing showers will affect the regional waters. A small northeasterly swell will continue to affect mainly the Atlantic waters and exposed passages. A more energetic northerly swell is expected to arrive late Monday night into Tuesday and persist through midweek, resulting in building seas. Beach Forecast Issued at 306am AST Sat Oct 17 2026 A north-northeasterly swell will maintain increased rip current risk through Monday along exposed northwest-, north- and northeast-facing beaches of Puerto Rico and the U.S. Virgin Islands. A more energetic northwesterly swell arriving late Monday into Tuesday will likely produce stronger rip currents and higher surf along exposed beaches, particularly across northern and northwestern Puerto Rico and the northern U.S Virgin Islands. These hazardous conditions will potentially persist through midweek. .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. |