textproduct: San Juan

KEY MESSAGES

Issued at 245 PM AST Tue Oct 27 2026

- Hot and humid conditions will continue through this afternoon, with the greatest heat impacts across coastal and urban areas of Puerto Rico and the U.S. Virgin Islands. Heat Advisories remain in effect.

- Showers and very isolated thunderstorms will continue to develop through the afternoon and evening, particularly across southern and southwestern Puerto Rico. Periods of heavy rainfall could lead to urban and small stream flooding, with isolated flash flooding possible.

- Another round of afternoon showers and isolated thunderstorms is expected on Wednesday, mainly across interior and western Puerto Rico. A gradual decrease in rainfall activity is anticipated on Thursday as drier air moves into the region.

- Although swell energy is gradually diminishing, hazardous surf conditions will persist through this evening, while life-threatening rip currents will remain a concern through at least early Wednesday. Spring tides will continue through October 30, potentially worsening coastal flooding in vulnerable areas during high tide.

Short Term(This evening through Thursday)

Issued at 245 PM AST Tue Oct 27 2026

Partly to mostly cloudy skies prevailed across the southern half of Puerto Rico today, while mostly clear skies dominated the northern half, Vieques, Culebra, and the US Virgin Islands. Passing showers affected southern Puerto Rico from the early through late morning hours, with rainfall accumulations near one inch in the wettest areas. Additional showers are expected this afternoon across southern Puerto Rico, potentially extending into the interior and northwestern municipalities as daytime heating, sea breeze convergence, and other local effects combine. The main impacts include ponding of water on roads and urban and small stream flooding, with a low chance of isolated flash flooding across southern Puerto Rico. A low risk of urban and small stream flooding also exists across northern Puerto Rico. Meanwhile, the prevailing southeasterly flow will continue to favor heat indices reaching Heat Advisory criteria in localized areas of north-central Puerto Rico through the remainder of today.

Tonight into Wednesday, a ridge over the eastern Caribbean is expected to gradually strengthen and extend across the region, promoting more stable conditions as moisture decreases. Southeasterly winds becoming more easterly, along with above-normal temperatures, will maintain warm and somewhat humid weather, although heat indices are less likely to reach Heat Advisory criteria. Wednesday and Thursday should be the driest and most stable days of the short-term period, with generally fair conditions across most areas. Nevertheless, isolated to scattered afternoon showers may develop over the interior and western Puerto Rico due to daytime heating and local effects. Any heavier showers could produce brief ponding on roads and in poorly drained areas, but the overall flooding threat will be lower than today. Although temperatures should be slightly lower, heat may still affect sensitive populations and those spending extended periods outdoors. Residents are encouraged to stay hydrated, take frequent breaks, and seek cooler environments when possible.

By late Thursday, an upper-level low moving northwestward toward the region is expected to gradually weaken the ridge and reduce subsidence aloft, marking a transition toward a potentially wetter pattern heading into the weekend.

Long Term(Friday through Tuesday)

Issued at 435 AM AST Tue Oct 27 2026

Some changes were introduced to the long-term forecast, as the wetter and unstable conditions may persist early next week. As mentioned in the previous discussions, a surface high lingering over the central Atlantic should maintain southeasterly winds on Friday and Saturday, but the steering flow may weaken and turn more easterly as an induced trough moves across the region, shifting back from the southeast by early Monday.

The weather conditions on Friday may be marginally unstable, though the latest model guidance suggest lingering dry air in the mid levels that may limit deep convection. Although showers and thunderstorms are expected Friday afternoon, flood potential will likely remain limited. Saturday onwards, trough deepening into the tropics should strengthen, weakening the mid-level ridge, and dominating the weather pattern across the CWA. Based on the latest model guidance, low and mid-level moisture should gradually increase across the area, reaching above-normal levels (> 60%) by Sunday and Monday.

In terms of instability, the trough should maintain cool mid- level temperatures (between -6 and - 8 C), with steep lapse rates and divergence aloft, allowing cloud growth and enhancing deeper convection across the area. Additionally, NCICS CFS continues to forecast the approach of the MJO over the local area, with a transition to a more convective environment across the Caribbean. Therefore, showers and thunderstorms can be expected during the night and morning hours Saturday onward, becoming more frequent on Sunday and Monday, particularly across the U.S. Virgin Islands and eastern/southeastern Puerto Rico. Afternoon convection should mainly concentrate across interior and western/northwestern Puerto Rico, including the San Juan Metro Area. Rainfall accumulations will likely lead to urban and small stream flooding, without ruling out localized flash flood, and rapid river rises. In addition, thunderstorms could lead to frequent lightning and gusty winds.

AVIATION

(18Z TAFS) Issued at 245 PM AST Tue Oct 27 2026

VFR conds expected across all terminals. SE winds at 10-15 kt with higher gusts thru 27/22Z, bcmg light from 27/22Z and 28/11Z. Brief MVFR condt possible at TJPS and TJBQ due to tsRA and VCTS thru 00Z. E winds from 28/11Z at 10-15 kt.

MARINE

Issued at 245 PM AST Tue Oct 27 2026

A long-period northerly swell continues to gradually subside across the Atlantic waters and local passages, as indicated by the latest nearshore buoy observations. However, seas up to 6 to 7 feet remain possible across portions of these waters through this evening. Small Craft Advisories remain in effect for the Atlantic offshore waters, the northern and northwestern nearshore waters, and the Mona Passage through 6 PM AST this evening. Meanwhile, surface high pressure over the central Atlantic will continue to promote moderate to locally fresh east- to southeasterly winds across the region through midweek. Strong showers and isolated thunderstorms remain possible mainly over the Caribbean waters, the Mona Passage, and offshore Atlantic waters at least through late tonight.

BEACH FORECAST

Issued at 245 PM AST Tue Oct 27 2026

Hazardous surf and rip current conditions continue along the north- facing beaches of Puerto Rico, Culebra, St. Thomas, and St. John due to a long-period northerly swell. However, nearshore buoy observations indicate that swell energy is gradually diminishing, with coastal conditions expected to improve through tonight. Nevertheless, breaking waves around 7 feet or greater remain possible along the most exposed beaches. Therefore, the High Surf Advisory remains in effect for the northern coastline of Puerto Rico, from Rincon to Fajardo, through 6 PM AST this evening.

A High Risk of Rip Currents remains in effect for the north-facing beaches of Puerto Rico, Culebra, St. Thomas, and St. John through at least early Wednesday morning. Although the rip current threat should gradually diminish as the northerly swell subsides, an extension of the High Risk may be necessary depending on nearshore conditions.

Additionally, spring tides, which contributed to elevated water levels this morning, are expected to persist through at least October 30. Therefore, despite the diminishing northerly swell, lingering coastal impacts could continue to be exacerbated during periods of high tide, including localized coastal flooding across vulnerable low-lying coastal areas.

Beachgoers are strongly urged to stay out of the water at beaches under a High Risk of Rip Currents and to heed all warning flags, posted signs, and instructions from lifeguards and local officials.

Please refer to the latest Coastal Hazard Message (CFWSJU) for updates, the most vulnerable areas, and additional information.

SJU WATCHES/WARNINGS/ADVISORIES

PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>013.

High Rip Current Risk through late tonight for PRZ001-002-005- 008-010-012.

High Surf Advisory until 6 PM AST this evening for PRZ001-002- 005-008-010.

VI...Heat Advisory until 5 PM AST this afternoon for VIZ001-002.

High Rip Current Risk through late tonight for VIZ001.

AM...Small Craft Advisory until 6 PM AST this evening for AMZ711-712- 741-742.