National Weather Service Today's Weather Impact Levels

072
FXCA62 TJSJ 200611
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
211 AM AST Mon Apr 20 2026

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

.KEY MESSAGES...
Updated at 155 AM AST Mon Apr 20 2026

* Limited flooding risk each afternoon, driven by locally induced
  convection.

* Isolated thunderstorms possible each afternoon, producing
  lightning and brief gusty winds.

* Choppy, wind-driven seas, subsiding on Tuesday, then build again
  Wednesday through Thursday with increasing seas and a northerly
  swell.

* Moderate rip current risk most days, potentially increasing to
  high by midweek along north and east-facing beaches.

&&

.Short Term(Today through Wednesday)...
Issued at 155 AM AST Mon Apr 20 2026

Overnight conditions were notably calm across Puerto Rico and the
U.S. Virgin Islands, with mostly clear skies prevailing. Winds
remained light and variable, similar to previous nights. Coastal
areas observed temperatures in the 70s, while interior locations
cooled into the 60s. Only a few brief passing showers were seen
over the surrounding waters, with little to no impact over land.
Overall, tranquil conditions dominated through the overnight
hours.

Looking ahead, a drier and more stable pattern will persist from
today through Wednesday, as a surface high pressure system over the
North Atlantic prevails, and promotes a generally easterly wind
flow. While some low-level moisture will remain in place, it will
become increasingly shallow, primarily confined below 700800 mb.
Today will feature mostly fair weather conditions, with limited
shower activity and minimal impacts.

On Tuesday, winds will weaken and shift from easterly to
east-southeasterly during the morning, then trend northeasterly
by the afternoon through Wednesday. This evolving wind pattern
will help steer locally induced convection toward southwestern and
southern Puerto Rico. Despite the drier air mass, sufficient low-
level moisture combined with daytime heating will support
scattered afternoon showers and isolated thunderstorms, followed
by improving conditions in the evening. By Wednesday, similar
conditions are expected, with stable weather prevailing and only
limited afternoon convection.

Flooding risk will remain generally limited through the period,
though localized impacts cannot be ruled out. Brief heavy showers
may result in ponding of water on roadways and in poor drainage
areas, along with minor urban and small stream
floodingparticularly in locations where soils remain saturated
from recent rainfall. Some rivers are still running elevated and
could respond quickly to additional rainfall. Overall, impacts are
expected to be localized and primarily confined to the afternoon
hours.

&&

.Long Term(Thursday through Monday)...
Issued at 155 AM AST Mon Apr 20 2026

A seasonal weather pattern is expected to prevail at the start of
the long-term period, with precipitable water values near
climatological normals and typical trade wind showers moving across
the local waters and windward sectors during the overnight and
morning hours. Afternoon convective development will remain possible
across interior and western portions of Puerto Rico, aided by
daytime heating, local effects, and sea breeze convergence. While
widespread rainfall risk is not anticipated early in the period,
moderate rainfall may still cause localized ponding in urban and
poorly drained areas, especially where showers persist or repeatedly
affect the same locations.

By late Thursday into Friday, a gradual increase in available
moisture is expected as the remnants of a frontal boundary linger
north of the region while low-level winds become more southerly.
This evolving pattern will promote warmer temperatures and a more
humid air mass across the islands. As a result, shower coverage
should become more numerous, with the greatest afternoon activity
focused over interior and northern to northwestern Puerto Rico,
although passing showers will remain possible elsewhere. Localized
urban and small stream flooding will become more likely where
stronger showers develop.

From Saturday through Monday, southeasterly to southerly flow is
forecast to persist and continue transporting tropical moisture into
the northeastern Caribbean. Precipitable water values are expected
to rise to above normal levels, supporting a wetter and more
unstable pattern. Combined with 925 mb temperatures trending above
climatological normal, daytime temperatures will likely rise above
seasonal values, particularly across coastal and urban areas of
Puerto Rico and the U.S. Virgin Islands. This will result in a
gradual increase in heat risk by the end of the period, especially
in lower elevations.

In this pattern, periods of locally heavy rainfall and isolated
thunderstorms will be possible each afternoon, particularly where
sea breeze convergence and local effects combine. Residents and
visitors should anticipate warmer and humid conditions, increased
potential for ponding of water on roadways, and localized flooding
in flood-prone areas through the latter part of the forecast
period.

&&

.AVIATION...
(06Z TAFS)
Issued at 155 AM AST Mon Apr 20 2026

Most TAF sites should experience VFR conditions. Periods of brief
MVFR with VCTS/SHRA after 12/17Z across TJSJ, TJPS, and TJBQ.
Prevailing winds should remain from east around 10 to 15 kts gusts
around 25 knots after 20/14Z or near VCTS/SHRA and with sea
breeze variations.

&&

.MARINE...
Issued at 155 AM AST Mon Apr 20 2026

A surface high positioned over the Atlantic is currently generating
moderate to locally fresh easterly winds, particularly affecting the
offshore Atlantic waters and the local Caribbean passages. This is
resulting in moderate to choppy sea conditions. Small Craft
Operators Should Exercise Caution in these aforementioned areas.
Sea states are anticipated to diminish slightly around Tuesday,
subsequently increasing to 6 to 7 feet from mid-week onward, owing
to a northerly swell propagating across the Atlantic waters. A
series of frontal lows and surface highs will result in winds
veering and backing during the week, with more ENE winds by
midweek and more ESE winds by the end of the workweek.

&&

.BEACH FORECAST...
Issued at 155 AM AST Mon Apr 20 2026

A moderate risk of rip currents (life-threatening rip currents are
possible in the surf zone) will be present at the north and east
facing beaches of Puerto Rico as well as beaches of Vieques,
Culebra, and the U.S. Virgin Islands to start the workweek.
Beachgoers should remain cautious due to these wind-driven seas. The
rip current risk is expected to decrease to low along the beaches of
the USVI and Vieques from Tuesday afternoon through early Wednesday
as winds lighten. Even if the risk for rip currents is low, life-
threatening rip currents often occur in the vicinity of groins,
jetties, reefs, and piers. Up to a moderate risk of rip currents is
forecast through early Wednesday. However, the risk of rip currents
is anticipated to potentially increase to high (life-threatening rip
currents are likely in the surf zone) along the northern coastline
of Puerto Rico by late Wednesday and Thursday, driven by a northerly
swell spreading across the Atlantic waters. Additionally, be weather-
aware for afternoon thunderstorms and rapidly changing conditions.
If you hear thunder, be prepared to seek shelter immediately. For
more information, please visit: weather.gov/beach/sju.

&&

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

$$

SHORT TERM/AVIATION...MMC
LONG TERM...CVB
MARINE/BEACH FORECAST...MRR

NWS SJU Office Area Forecast Discussion