textproduct: San Juan

KEY MESSAGES

Issued at 306 AM AST Sat Oct 17 2026

* Warm conditions may affect heat-sensitive individuals, especially without adequate hydration or access to cooling.

* Afternoon showers are expected across interior and northwestern Puerto Rico and the San Juan metro area, with localized ponding possible. * An arriving swell will increase the risk of life-threatening rip currents along exposed beaches.

* Brief passing showers may affect windward areas and the U.S. Virgin Islands, with generally limited rainfall accumulations.

Short Term(Today through Monday)

Issued at 306 AM 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.

AVIATION

(06Z TAFS) Issued at 306 AM AST Sat Oct 17 2026

VFR conditions are expected to prevail across most terminals.Brief SHRA may affect eastern PR and USVI terminals this morning. Afternoon SHRA may develop across interior and northwestern PR. VCTS are possible at TJBQ and TJSJ, mainly after 17/18Z with a reduction in VIS AND CIGS. Brief MVFR conditions are possible in heavier SHRA. Mountain obscurations are possible with afternoon activity. Easterly winds will gradually veer to the SE around 17/18Z.

MARINE

Issued at 306 AM 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 306 AM 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.