National Weather Service Today's Weather Impact Levels

429
FXCA62 TJSJ 190539
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
139 AM AST Thu Mar 19 2026

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

.KEY MESSAGES...
Issued at 132 AM AST Thu Mar 19 2026

* Hazardous seas and life-threatening rip currents continue across
  the Atlantic waters, and along the north and eastern beaches of
  the islands.

* Fair weather conditions and warmer than normal temperatures are
  expected across the U.S. Virgin Islands today. Similar
  conditions are expected for Puerto Rico, with showers
  developing over the NW sections this afternoon.

* A frontal boundary and associated trough will increase shower
  activity from late this week into the weekend, bringing periods
  of unsettled weather across Puerto Rico and the U.S. Virgin
  Islands.

&&

.Short Term(Today through Saturday)...
Issued at 132 AM AST Thu Mar 19 2026

Mostly clear to partly cloudy skies were observed across the islands
during the night. Passing showers were noted mainly across the
eastern and southern portions of Puerto Rico. Minimum temperatures
were from the mid-70s across the coastal areas of the islands to the
lower 60s in the higher elevations of Puerto Rico. The wind was from
the east around 10 mph, with land breeze variations.

Current model guidance suggest that the region will remain under the
influence of an upper level ridge, providing warmer 500 mb
temperatures (stable conditions aloft), and moderate to light
southeasterly trade winds, that will bring periods of dry/moist air
through Friday. Therefore, similar conditions are expected today and
tomorrow, with passing showers prevailing across windward areas
during the night/morning hours, followed by afternoon showers
developing over portions of north-northwest PR. A limited flood risk
is expected with this activity as localized rainfall accumulations
are expected to remain under an inch.

A weather pattern change is expected from late Friday into Saturday.
Latest Total Precipitable Water imagery highlights a deep moisture
plume trailing a boundary to the northwest over the western Atlantic
and the Bahamas, which global models are gradually edging closer to
the region by the end of the workweek. Forecast soundings show a
sharp increase in moisture profiles by Saturday. PWAT values are
forecast to surge above the 75th percentile (reaching up to 1.75
inches), accompanied by significant spikes in both the 850-700mb and
700-500mb relative humidity layers. In addition, lighter steering
winds are expected as the frontal boundary moves closer to the
region, with 925 mb wind speeds decreasing substantially from 15-20
knots today, down to 5-10 knots over the weekend. This combination
of pooling moisture and a weak steering flow will result in
increased shower coverage. Therefore,  a wetter start to the weekend
is expected.

&&

.Long Term(Sunday through Thursday)...
Issued at 132 AM AST Thu Mar 19 2026

A mid level trough will cross the region on Sunday, while most of
its energy remains north of the area, supporting stronger winds
aloft and unstable conditions. A pre frontal trough over the area
early in the period will promote light and variable winds, becoming
calm at times. Behind it, surface high pressure building over the
western Atlantic will bring a gradual shift to north easterly winds
through midweek. Another mid level trough and associated frontal
boundary will approach late Wednesday into Thursday. Moisture will
increase from near normal early in the period to above normal by
Tuesday onward, with deep moisture in place through the rest of the
forecast. Mid level temperatures will remain near normal with
occasional cooling aloft, while increased cloud cover and north
easterly winds will support a gradual cooling trend.

Unsettled weather conditions will persist with elevated risk of
excessive rainfall and thunderstorms each day. Slow moving showers
early in the period will increase the risk of flooding in urban
areas and small streams. As north easterly winds develop, showers
will become more frequent across windward areas, with afternoon
activity over interior and western Puerto Rico. From Tuesday onward,
deeper moisture will support more efficient rainfall, increasing the
flooding risk. Thunderstorms may produce lightning and gusty winds.
Residents and visitors should remain alert for periods of heavy rain
and thunderstorms.

&&

.AVIATION...
(06Z TAFS)
Issued at 132 AM AST Thu Mar 19 2026

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. Mostly VCSH expected across the area
terminals. Low-level winds ESE at 10-20 kt, with sea breeze
variations expected at TJBQ aft 19/14z.

&&

.MARINE...
Issued at 132 AM AST Thu Mar 19 2026

As a frontal boundary and pre frontal trough approach the region,
winds will veer from the east southeast and gradually diminish, with
locally higher winds possible today across the Mona Passage. Seas
will slowly subside, but choppy to rough conditions will persist
across portions of the local waters. A Small Craft Advisory remains
in effect for the offshore Atlantic waters through this afternoon,
with Small Craft Should Exercise Caution conditions elsewhere.
Winds will shift back from the northeast early next week, with
marine conditions generally improving, although unsettled weather
will persist.

&&

.BEACH FORECAST...
Issued at 132 AM AST Thu Mar 19 2026

A high risk of rip currents persist along all northern and
eastern beaches of Puerto Rico, as well as across Vieques,
Culebra, and the U.S. Virgin Islands. These conditions are life
threatening, and a High Rip Current Risk remains in effect for
these areas. Beachgoers should avoid entering the water in exposed
areas.

Conditions will gradually improve as winds and seas diminish.
However, a moderate risk of rip currents will persist along north
and east facing beaches, meaning dangerous currents will remain
possible even as conditions appear calmer. Even when the risk is
low, rip currents can still occur near groins, jetties, reefs, and
piers. Residents and visitors should continue to monitor the
forecast and exercise caution.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for PRZ001>003-005-
     008-012-013.

VI...High Rip Current Risk through this afternoon for VIZ001-002.

AM...Small Craft Advisory until 6 PM AST this evening for AMZ711.

&&

$$

SHORT TERM...DSR
LONG TERM/BEACH/MARINE...ICP
AVIATION...DSR

NWS SJU Office Area Forecast Discussion