textproduct: San Juan

KEY MESSAGES

Updated at 215 AM AST Fri Apr 24 2026

* Pulses of northerly swell will continue into early next week, maintaining a moderate rip current risk along north-facing beaches of Puerto Rico, Culebra, Vieques, and the U.S. Virgin Islands, and occasionally producing locally hazardous marine conditions.

* Flooding risk remains limited overall, with locally elevated risk at times into early next week, mainly from slow-moving afternoon convection across Puerto Rico.

* A warming trend will develop through the weekend into early next week, with heat indices near or above 100F possible, especially in coastal and urban areas.

* Across the U.S. Virgin Islands, moderate rip current risk will persist, along with warmer conditions and periods of ponding of water possible early next week.

Short Term(Today through Sunday)

Issued at 215 AM AST Fri Apr 24 2026

Tranquil conditions observed overnight will continue through the morning hours, with mostly fair weather expected across Puerto Rico and the U.S. Virgin Islands. A weak and evolving pattern will persist, influenced by a fading frontal boundary just north of the region and lingering troughing across the northeastern Caribbean. Low-level flow will remain mainly east to southeast today, gradually veering and supporting the onset of a warming trend. With light to gentle winds and weak steering flow, afternoon convection is expected to develop over the interior of Puerto Rico due to diurnal heating and sea-breeze convergence, then expand toward surrounding coastal areas. Activity should remain mostly shallow to moderate, although slow-moving showers could produce locally higher rainfall totals. An isolated thunderstorm cannot be ruled out. A brief increase in winds is expected tonight into early Saturday as the pressure gradient tightens slightly, allowing for a few passing showers, mainly across windward areas.

Through the weekend, the boundary is forecast to transition into a trough while lifting away from the region, with weak low pressure development along this feature well to the northwest helping to modify the regional flow. At the same time, a weak high over the western Atlantic will drift southeastward and weaken, resulting in a lighter pressure gradient and a more established southeasterly to southerly wind pattern. Saturday should be somewhat drier aloft, with subsidence and a persistent trade wind cap limiting vertical development despite warmer conditions. By Sunday, moisture is expected to increase and the inversion weakens, allowing for greater cloudiness and more active afternoon convection. Winds veering to the south to southwest may allow activity to reach northern Puerto Rico, including the San Juan metro area.

The primary hazard will be localized flooding from slow-moving showers, mainly across interior and urban areas of Puerto Rico. The risk remains limited today, decreases further on Saturday, then increases slightly by Sunday as moisture deepens. Isolated thunderstorms remain possible, and the warming trend will lead to near to above normal temperatures by the end of the period.

Long Term(Monday through Friday)

Issued at 215 AM AST Fri Apr 24 2026

A strengthening high-pressure system over the central Atlantic will maintain a consistent south-southeasterly wind flow across the region. Simultaneously, a deepening upper-level trough will create unstable conditions aloft. This pattern will bring abundant moisture from the Caribbean into the islands, significantly increasing the potential for showers and thunderstorms.

A gradual increase in moisture is expected from Monday through Wednesday, with precipitable water values reaching up to 2.25 inches; the bulk of this moisture is anticipated to arrive by Tuesday afternoon. Consequently, shower activity is anticipated during the morning hours across the U.S. Virgin Islands and eastern Puerto Rico. By the afternoon, the combination of daytime heating, local effects, and abundant moisture will likely trigger moderate to heavy rainfall across the interior and western portions of Puerto Rico. While temperatures at 500 mb will remain near seasonal averages (between -7 to -8C), there is sufficient atmospheric dynamics to support thunderstorm activity.

As winds prevail from the south-southeast, temperatures at the 925 mb level will rise well above climatological norms from Monday through the latter part of the week. Maximum surface temperatures are expected to range from the upper 80s to low 90s in coastal and urban areas, and the low to mid-80s in higher elevations. Due to high humidity values and southerly flow, heat indices will likely surpass 100F daily. Residents and visitors are strongly encouraged to prioritize hydration and limit prolonged sun exposure to stay safe during this period of excessive heat.

AVIATION

(06Z TAFS) Issued at 215 AM AST Fri Apr 24 2026

VFR conds will prevail at all TAF sites thru the fcst pd. Slow- moving VCSH expected across all PR terminals btw 24/1622Z, and across USVI terminals from late mrng onward. Winds lgt/vrb, bcmg sea breeze dominated with speeds around 810 kt during the aftn, then returning to lgt/vrb ovrnght.

MARINE

Issued at 215 AM AST Fri Apr 24 2026

A weak frontal boundary meandering just north of the region will continue to weaken and transition into a trough while lifting away, while a surface high over the southwestern Atlantic shifts east into the central Atlantic. This pattern will maintain light east to southeast winds today, followed by a brief increase and a veering to a more southerly flow into early Saturday before easing again through the weekend. Residual northerly swell will continue to subside, with a small, long-period NNE swell expected to arrive by Saturday into early next week with limited impacts. Overall, marine conditions will gradually improve and remain below advisory levels, although scattered showers may still produce locally higher winds and seas.

BEACH FORECAST

Issued at 215 AM AST Fri Apr 24 2026

A moderate risk of rip currents will persist through midweek across the northern beaches of Puerto Rico, as well as Culebra, Vieques, and the U.S. Virgin Islands. This means rip currents are possible and can still be life-threatening, especially for inexperienced swimmers. Conditions are expected to gradually improve across the islands during the first half of next week as the influence of long-period northerly swell diminishes. Meanwhile, a low risk will continue along south-facing beaches.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...None.