Marine Weather and Tide Forecast for Lamboglia, PR

.Short Term(This evening through Monday)...
Issued at 203 PM AST Sat Oct 17 2026

A patch of moisture, with GOES-19-derived total precipitable water estimates ranging from 1.5 to 1.9 inches, supported brief, passing showers across the local waters and windward portions of Puerto Rico and the U.S. Virgin Islands this morning. By around 11 AM AST, showers had spread farther west into Puerto Rico. Doppler radar detected the San Juan Streamer developing downwind from the Yunque into the San Juan Metropolitan area. Another area of convection developed from Coamo's mountains into the west coast of PR. East-southeast winds ranged from 5 to 15 mph, with higher gusts and local sea breeze variations. Temperatures reached the upper 80s to lower 90s and, combined with high surface humidity, resulted in heat indices of 100 to 107 degrees Fahrenheit.

A building mid- to upper-level ridge will promote subsidence, while drier air at those levels will limit widespread convection this afternoon. Nevertheless, available moisture, daytime heating, sea breeze convergence, and terrain effects will support localized showers and thunderstorms, mainly across interior, north-central, and northwestern Puerto Rico. Additional showers may develop downwind of St. Thomas, St. Croix, Vieques, and Culebra and move over adjacent waters. The flood threat will remain limited, with heavier showers potentially producing ponding of water on roads and in poorly drained areas. Isolated urban and small stream flooding cannot be ruled out across northeastern, northwestern, and interior Puerto Rico.

Overnight into early Sunday morning, patches of moisture embedded in the prevailing east-southeast flow will bring occasional passing showers, mainly to windward areas. Leeward locations will generally experience mostly clear skies between showers.

By Sunday afternoon and continuing into Monday, a mid- to upper- level low northeast of the region is expected to weaken the ridge's influence, allowing a more favorable environment for afternoon and evening convection. Additional moisture and local convergence will increase the potential for heavier showers and stronger thunderstorms, particularly across interior and northern Puerto Rico. Weak steering flow may favor slow-moving cells and repeated development over the same areas, increasing the potential for localized rainfall accumulations and flooding. The Hazardous Weather Outlook has been updated to reflect the increased thunderstorm and flooding potential for both days.

.Long Term(Tuesday through Saturday)...
Issued at 306 AM 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 the weather conditions as they evolve.

AVIATION
(18Z TAFS)
Issued at 203 PM AST Sat Oct 17 2026

The likelihood of -TSRA in increasing in the TAF prd, though VFR conds should persist across all terminals. Aftn cvnt will cont to bring -SHRA/+SHRA, though JBQ remains with VCTS and TEMPO btwn 1719- 21z due psbl -TSRA. E-ESE btwn 10 - 15 kt will cont this aftn, becoming light and VRB aft 17/23z. -SHRA may move across USVI TAFs around 18/06z, reducing CIGs /VIS and leading to tempo MVFR conds.
Winds should pick up by 18/12-14z btwn 8 - 12 kt, though steering flow will remain weak.

MARINE
Issued at 203 PM AST Sat Oct 17 2026

As a surface low and its associated frontal boundary move across the western Atlantic, the local pressure gradient will weaken, supporting gentle to moderate east-southeast winds through the weekend into early next week. A small northerly swell will gradually subside tonight across the Atlantic waters and exposed passages. A more energetic northerly swell will arrive Monday night, peak Tuesday, and persist through midweek, resulting in building seas. Isolated thunderstorms may develop over the coastal waters each afternoon this weekend, with activity potentially extending into the evening on Sunday and Monday.

BEACH FORECAST
Issued at 203 PM AST Sat Oct 17 2026

A moderate risk of rip currents will persist this afternoon along Puerto Rico's Atlantic shoreline and the U.S. Virgin Islands, particularly at north-facing beaches. A more energetic northwesterly swell will arrive Monday evening, build into Tuesday, and become northerly by Wednesday. This swell will increase surf heights and the risk of life-threatening rip currents along exposed beaches, with hazardous conditions potentially persisting through midweek. Afternoon thunderstorms may bring lightning and locally gusty winds to beaches each day.
Beachgoers should leave the water and seek shelter when they hear thunder.

SJU WATCHES/WARNINGS/ADVISORIES
PR...None.
VI...None.
AM...None.