495
FXCA62 TJSJ 270715
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
315 AM AST Mon Apr 27 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST...

.KEY MESSAGES...
Updated at 304 AM AST Mon Apr 27 2026


* A gradual increase in moisture is expected today, enhancing the
  potential for showers and isolated thunderstorms across Puerto
  Rico and the U.S. Virgin Islands through at least midweek, with
  increased flooding and lightning risk.

* A warming trend is likely across the islands, particularly at
  urban and coastal sites, with above-normal temperatures through
  the weekend. Heat indices are expected to reach or exceed 100F,
  affecting the more vulnerable communities.

* A moderate risk of rip currents will persist along north-and
  east-facing beaches of Puerto Rico and the U.S. Virgin Islands
  as pulses of a small northeasterly continues to reach the region.
  Rip currents are possible and can be life-threatening. Please
  exercise caution along exposed beaches.

&&

.Short Term(Today through Wednesday)...
Issued at 304 AM AST Mon Apr 27 2026

A calm and quiet night prevailed across Puerto Rico and the U.S.
Virgin Islands, with only a few passing showers over the Atlantic
and Caribbean waters. Overnight temperatures remained slightly warm
across the region, ranging from the mid-70s to low 80s across urban
and coastal areas. In higher elevations, temperatures stayed in the
mid 60s to low 70s. Winds remained light and variable at 5 knots or
less.

Starting this morning, a gradual increase in low-level moisture is
expected to transition the region into a much wetter pattern through
at least midweek. Recent precipitable water analysis suggests above-
normal moisture arriving from the Caribbean Sea and northern South
America, with values reaching 2.0 to 2.2 inches through Wednesday.
As this deepening moisture interacts with a mid- to upper-level
trough lingering over the region, it will promote atmospheric
instability. At the surface, high pressure will maintain light south-
southeasterly winds.

This pattern will support frequent showers and isolated
thunderstorms, particularly during the afternoon hours over the
interior and northern portions of Puerto Rico. Due to the light
winds, shower activity will move slowly and expand in coverage,
persisting over the region for longer durations. Consequently, the
risk of flooding will be elevated from today through midweek,
especially during the afternoon and evening. Periods of heavy
rainfall, lightning, and ponding on roadways are likely, with
localized flooding developing where rain persists.

Additionally, a limited heat risk continues each day due to the
combination of above-normal temperatures, southeasterly flow, and
increasing humidity. In areas where rain has yet to develop, a
warming trend is expected, driven by the southerly wind flow and
above-normal sea surface temperatures across the regional waters.

&&

.Long Term(Thursday through Monday)...
Issued at 304 AM AST Mon Apr 27 2026

As mentioned in previous discussions, a moist and unstable weather
pattern will persist from Thursday through Friday across Puerto Rico
and the U.S. Virgin Islands, accompanied by light to moderate south-
southeasterly winds. This southerly flow will promote warm
temperatures and elevated humidity. Residents and visitors are
encouraged to monitor the forecast, stay well hydrated, take
frequent breaks from the heat, and limit prolonged sun exposure,
particularly during the warmest hours of the day.

From Thursday through Friday, moisture levels will remain above
normal for this time of year, supporting a pattern of daily showers
and isolated thunderstorms. The most active convection is expected
to develop during the afternoon across the interior and northern
portions of Puerto Rico, while morning activity will favor southern
and eastern Puerto Rico as well as the U.S. Virgin Islands. A
gradual drying trend will begin on Saturday, leading to improving
conditions through the weekend. The driest period is expected from
Sunday into Monday, when more stable conditions take hold across the
region. Although afternoon showers may still develop, their coverage
and intensity will decrease. By this time, any shower activity
should be brief and limited.

Warm conditions will persist throughout the period due to the
prevailing south-southeasterly flow. Temperatures at the 925 mb
level will remain above normal through Friday before gradually
easing over the weekend. Maximum surface temperatures will range
from the upper 80s to low 90s across coastal and urban areas, and
from the low to mid 80s in higher elevations. Combined with high
humidity, heat indices are expected to exceed 100 degrees Fahrenheit
daily, especially through Friday with slight moderation by late
weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 304 AM AST Mon Apr 27 2026

Mainly VFR conds expected. Light/variable to calm winds early in the
morning, becoming SSE btw 8-10 kt after 27/14Z. Later in the
afternoon hours, SHRA/TSRA may develop over interior/western PR and
affect TJSJ/TJBQ btw 27/17-23Z, causing brief MVFR/IFR conds. VCSH
are possible over eastern PR/USVI after 27/23Z. Winds decrease again
to light/variable during the overnight hrs.

&&

.MARINE...
Issued at 304 AM AST Mon Apr 27 2026

A surface high-pressure system over the central Atlantic will
continue to weaken, while a surface low strengthens over the
northwestern Atlantic over the next few days. This weakening
pressure gradient will promote light to gentle southeasterly winds
through at least midweek, becoming more easterly by the latter part
of the week. Pulses of small, long-period northeasterly swell will
continue to spread across the Atlantic waters and local passages
over the next few days. The likelihood of showers and thunderstorms
will also increase through at least midweek.

&&

.BEACH FORECAST...
Issued at 304 AM AST Mon Apr 27 2026

Today, there is a moderate risk of rip currents along the north-
facing beaches of Puerto Rico, Culebra, St. Croix, St. Thomas, and
St. John, as a small northeast swell spreads across the Atlantic
waters, increasing the potential for life-threatening rip currents.
A moderate risk means that life-threatening rip currents are
possible in the surf zone. Beachgoers should exercise caution,
particularly in those exposed areas. This moderate risk is expected
to persist through most of the week, while beaches along the
southern coastlines remain at a low risk of rip currents.

Keep an eye out for quick changes in the weather conditions with
afternoon thunderstorms across portions of Puerto Rico and the U.S.
Virgin Islands, which could bring strong, gusty winds and lightning.
Seek shelter immediately if you hear thunder. For additional
information and location-specific rip current details, visit:
weather.gov/beach/sju.

&&

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

$$

SHORT TERM...GRS
LONG TERM...MMC
MARINE/BEACH FORECAST...YZR

NWS SJU Office Area Forecast Discussion