Your Number One Source for Real-Time Puerto Rico Weather & Hurricane Tracking Updates

248
FXCA62 TJSJ 191753
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
153 PM AST Thu Mar 19 2026

...New SHORT TERM, AVIATION, MARINE, BEACH FORECAST, FIRE WEATHER...

.KEY MESSAGES...
Issued at 153 PM AST Thu Mar 19 2026

* Showers will affect the eastern and northwestern sections of
  Puerto Rico over the next few hours, while mainly fair weather
  prevails across the U.S. Virgin Islands.

* Passing showers are expected across windward areas of the
  islands during the night and morning hours.

* Life-threatening rip currents will remain possible (moderate
  risk) along north-facing beaches of Puerto Rico, Culebra, and
  the U.S. Virgin Islands on Friday and throughout the weekend.

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

&&

.Short Term(This evening through Saturday)...
Issued at 153 PM AST Thu Mar 19 2026

Some streamer activity developed this morning downwind of the
smaller islands and El Yunque under a southeasterly wind flow.
However, associated shower activity produced minimal rainfall
accumulations. A similar pattern is expected to persist, with
isolated to scattered showers developing across the interior and
western to northwestern portions of Puerto Rico, resulting in
limited rainfall totals.

Currently, a polar trough and its associated frontal boundary remain
well northwest of the forecast area, with the southern extent of the
boundary affecting eastern Cuba. Surface high pressure over the
north-central Atlantic, in combination with the frontal boundary,
continues to promote a southeasterly wind flow across the region.
Additionally, ridging aloft will support generally stable
conditions. This pattern will favor above-normal surface
temperatures and below-normal to near-normal moisture levels through
Friday.

Therefore, similar weather conditions are expected to prevail, with
mostly fair weather and warmer conditions with a few passing showers
during the overnight and early morning hours across windward coastal
areas. By Friday afternoon, shallow convective activity is expected
to develop across interior and western to northwestern Puerto Rico.

However, weather conditions are expected to deteriorate from Friday
night into the weekend gradually. The approaching polar trough will
increase instability aloft as the associated frontal boundary moves
closer from the northwest. Despite this, uncertainty remains, as the
most active portion of the trough is forecast to remain north of the
region, with the strongest dynamics (a 75-80 knots 250 mb jet)
staying north of Puerto Rico.

Even though an increase in tropical moisture is expected due to
southerly flow, with precipitable water values rising above normal
levels and steeper lapse rates developing between the 850-700 mb and
700-500 mb layers, model guidance continues to suggest limited
rainfall accumulations overall on Saturday. Furthermore, afternoon
convection will depend heavily on cloud cover associated with the
approaching boundary, which may inhibit thunderstorm development.

Nevertheless, isolated activity remains possible. Given the presence
of a nearby col leading to weak steering winds, any heavier showers
that develop could persist over localized areas, potentially
increasing the flooding risk in flood-prone areas.

&&

.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...
(18Z TAFS)
Issued at 153 PM AST Thu Mar 19 2026

Mainly VFR conds expected to prevail across all terminals thru
the fcst pd. VCSH will cont across the area, with brief SHRA
possible, mainly ovr interior/wrn PR and and within streamers
downwind of the smaller islands. Brief MVFR conds are possible.
Sfc winds fm ESE at 1016 kt with sea breeze variations and
occasional higher gusts. Winds bcm lighter/vrb overnight, then
incr again aft 20/13Z.

&&

.MARINE...
Issued at 153 PM AST Thu Mar 19 2026

As a frontal boundary and pre-frontal trough approach the region,
winds will veer from the east-southeast through the weekend and
become light to gentle. Seas will slowly subside, but choppy to
rough conditions will persist across the offshore Atlantic waters
through at least this afternoon where a Small Craft Advisory
remains in effect. Winds will shift back to the northeast early
next week, marine conditions generally improving with seas around
2 to 4 feet across the local waters, however an unsettled weather
will persist resulting in better chances for rain.


&&

.BEACH FORECAST...
Issued at 153 PM AST Thu Mar 19 2026

A High Rip Current Risk remains in effect along all northern,
eastern, and southeastern beaches of Puerto Rico, as well as
across Vieques, Culebra, and the U.S. Virgin Islands through this
afternoon. These conditions are life-threatening, and beachgoers
should avoid entering the water in exposed areas.

From tonight through the weekend, as winds gradually become
lighter, a moderate risk of rip currents will prevail along north-
facing beaches of Puerto Rico, Culebra, and the U.S. Virgin
Islands, while a low risk is expected along more protected
southern beaches. A moderate risk means that life-threatening rip
currents are still possible in the surf zone, and beachgoers
should remain alert and cautious. Residents and visitors are
encouraged to monitor the forecast for updates or changes. For
additional information and location-specific rip current details,
please visit: weather.gov/beach/sju.

&&

.FIRE WEATHER...
Issued at 153 PM AST Thu Mar 19 2026

From around 11 AM AST into the early afternoon hours, the Cabo
Rojo and Guanica RAWS surface stations reported minimum relative
humidity in the low to mid-50% range, with SE winds around 10 to
15 mph and gusts of 24 to 26 mph. The KBDI in Cabo Rojo remains
above the critical threshold. With these borderline conditions,
the risk of fire remains low over the next hour or two. Relative
humidity is expected to increase through the rest of the
afternoon, reducing the overall risk. Tomorrow, similar borderline
conditions are possible. Over the weekend, no fire threat is
expected, as a frontal boundary and associated trough will bring
increased moisture to the area, and winds will be very light.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk until 6 PM AST this evening for PRZ001>003-
     005-008-012-013.

VI...High Rip Current Risk until 6 PM AST this evening for VIZ001-002.

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

&&

$$

SHORT TERM/AVIATION...CVB
LONG TERM...ICP
MARINE/BEACH/FIRE...YZR

NWS SJU Office Area Forecast Discussion