Marine Weather and Tide Forecast for Luis M. Cintrón, PR

SHORT TERM
Tonight through Monday...

Current shower and isolated t-storm activity currently over the western half of PR will gradually dissipate and/or move offshore as we head into the evening. Heat index values up to 100 to 104F have been reported by several coastal official and unofficial stations.
PWAT values of 1.7 to 1.8 and locally up to around 2.00 in during the afternoon will gradually decrease tomorrow. A mid to upper level ridge will continue to hold during the weekend, promoting dry air intrusion and stable conditions aloft. The 12Z sounding detected a trade wind cap at around 800mb, this general pattern will continue during the next few days with available moisture remaining below 800 mb. Upper-level lows north of the islands will remain north of the islands during the weekend, possibly approaching on Monday.
Lingering low concentrations of Saharan Dust will persist during the weekend, albeit gradually decreasing. For Monday and into the long term period, however, Saharan Dust concentrations will gradually start to increase. A broad surface high pressure over the Atlantic will continue to promote moderate to locally fresh E to ESE steering flow during the period, with sea breeze variations and local effects. Normal to above normal temperatures will continue during the period. The diurnal pattern will continue tomorrow, with passing showers reaching the eastern region, especially during the mornings and overnight hours, and with afternoon showers and thunderstorms mainly over interior to western Puerto Rico due to sea breeze convergence, diurnal heating and local effects. On Monday, a tropical wave (currently with its axis just east of 45W and with most of its related moisture between 5 to 15N) will enter the eastern Caribbean Sea. Although most of its bulk of moisture will remain south of the local islands. Peripheral moisture will increase precipitable water (PWAT) values to 1.90 to around 2.00 inches on Monday. This moisture along with instability from the wave will increase shower and thunderstorm activity mainly during the afternoon to evening hours as it boosts the diurnal pattern.

LONG TERM
Tuesday through Saturday...

/FROM PREV DISCUSSION
Issued at 517 AM AST Sat Jun 21 2025/

A Saharan Air Layer with moderate concentrations of Saharan dust will move across the islands on Tuesday. This will promote hazy skies, reduced visibilities, and poor air quality. East to southeast winds are expected to promote warmer than normal temperatures early in the week. A broad surface high pressure extending from the central Atlantic and a strong 850-700mb ridge developing northeast of the region will promote breezy conditions and drier air intrusion through Thursday. Therefore, mostly fair weather conditions are expected through the end of the week, with showers and isolated thunderstorms developing each afternoon over western PR. However, a trade wind perturbation will bring a small surge in moisture content between late Thursday and Friday. The next tropical wave is expected to move mainly south of the region once again by Saturday.

AVIATION

(18Z TAFS)

Mainly VFR conditions across the terminals. TJBQ VCTS through 21/22Z and VCTY showers is possible tonight over eastern terminals tonight. E-ESE winds up to 15-20 kts with higher gusts will continue through 21/23Z. Winds decreasing to around 5-10 kts after before increasing again after 22/13Z to 15-20 kts with higher gusts and sea breeze variations.

MARINE

A subtropical Atlantic ridge extending southward into the northern Caribbean continues to promote moderate to locally fresh easterly winds, resulting in choppy seas over portions of the local Atlantic and Caribbean waters, and local passages. Therefore, small craft should exercise caution. The next tropical wave should approach the local waters by next Monday.

BEACH FORECAST

Tonight, there is a moderate risk of rip currents for the northwestern beaches of Puerto Rico, as well as for beaches of St. Croix. Beachgoers must exercise caution due to life- threatening rip currents along exposed unprotected beaches across these areas. Elsewhere the risk is low, however, life- threatening rip currents often occur in the vicinity of groins, jetties, reefs, and piers. For tomorrow, a moderate risk of rip currents will continue for St. Croix, with southeastern PR increasing to moderate tomorrow night.

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