273
FXCA62 TJSJ 291815
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
215 PM AST Sun Mar 29 2026

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

.KEY MESSAGES...
Issued at 207 PM AST Sun Mar 29 2026

* Mainly fair weather is expected across the U.S. Virgin Islands
  and Puerto Rico through the next few days. However, passing
  trade wind showers will bring brief periods of rain, especially
  Monday through Tuesday.

* Localized afternoon showers are expected over southwest Puerto
  Rico today, followed by increasing overnight and morning showers
  across windward areas as moisture increases.

* A weak frontal boundary will increase moisture and instability
  by Tuesday, increasing the likelihood of showers and isolated
  thunderstorms, mainly Tuesday afternoon into evening.

* Hazardous marine and coastal conditions will develop late
  Monday through at least Thursday, driven by a long-period
  northerly swell and strengthening winds, resulting in a high
  surf, life- threatening rip currents, and possible Small Craft
  Advisory conditions.

&&

.Short Term(This evening through Tuesday)...
Issued at 207 PM AST Sun Mar 29 2026

Fair weather prevailed today across Puerto Rico and the U.S.
Virgin Islands, with little to no rainfall. Winds were from the
northeast at 5 to 15 mph. Despite generally dry conditions, a few
passing showers developed over windward areas. By midday,
cloudiness increased across the mountains and southern slopes,
particularly in southwestern Puerto Rico, with streamers moving
from the U.S. Virgin Islands into nearby waters. Temperatures
reached the mid-80s in coastal and urban areas and the upper 70s
in the mountains.

Although drier air is moving into the region, isolated afternoon
showers remain possible, mainly across southwestern Puerto Rico
and the southern slopes. Brief trade wind showers may also
continue at times over windward areas.

Looking ahead, northeasterly winds will persist through Monday
and Tuesday, bringing periodic increases in moisture. Winds are
expected to strengthen Monday evening as a frontal boundary
approaches. This will allow moisture to build across the region,
leading to more frequent showers. The highest chances of rainfall
are expected: early Monday morning, Monday afternoon, Late Monday
night into early Tuesday, and Tuesday afternoon.

By Tuesday afternoon, lingering moisture associated with a
surface trough low off to the northeast over the Atlantic, along
with the approaching frontal boundary, may further enhance shower
activity and the potential for thunderstorms, elevating the
flooding risk for the islands.

Meanwhile, hazardous coastal conditions will develop, especially
along north-facing beaches of Puerto Rico and the U.S. Virgin
Islands. A long-period northerly swell will bring: High surf,
Life-threatening rip currents, and Possible coastal erosion. If
you plan to visit the beach, use extreme caution and consider
south- or Caribbean-facing beaches, where conditions are safer.

&&

.LONG TERM...
Issued at 433 AM AST Sun Mar 29 2026

High pressure centered well north in the Atlantic and an induced
surface trough northeast of the islands will maintain a strong
northeasterly wind flow through the end of the week. As the surface
trough moves north of the island on Friday and the weekend, the
winds will shift from the southeast. It will be breezy through at
least Thursday, with speeds of 15 to 20 knots. On Wednesday and
Thursday, under the northeasterly wind flow, the surface trough will
push a drier air mass above the 700 mb-layer into the northeastern
Caribbean. As a result, precipitable water values will drop to near
normal values for this time of the year. On these days, the focus of
rain should be in the northeast and the Virgin Islands early in the
day, followed by stronger showers in the afternoon for the interior
and southwest. The atmosphere does not look particularly favorable
for heavy rainfall accumulations, although the mid-levels will be
cool enough for at least for isolated lightning each afternoon.

Moving into the end of the week and the weekend, a new upper level
low will dig from the southeastern United States. For Friday and
Saturday, the latest guidance show a vorticity maximum at the upper
levels, with some low level convergence too. However, some dry
intrusion persist in the mid-levels. Since the winds will shift
from the southeast, diurnal heating is expected to be stronger.
Therefore, there is a medium chance that showers may grow enough to
break through the drier air, and reaching the favorable conditions
aloft. For now, the forecast call for stronger thunderstorms in the
afternoon hours, but moderate rainfall accumulations, focused along
the interior and western municipalities of Puerto Rico.

&&

.AVIATION...
(18Z TAFS)
Issued at 207 PM AST Sun Mar 29 2026

VFR conditions across all TAF sites. Aft convection will bring VCSH
over TJPS, TJSJ, and TIST btwn 29/18-23Z. Additional, showers will
affect TJSJ, TJBQ, and TIST from 30/03-12Z, as pockets of moisture
filters inland. Winds will strengthen from tomorrow onwards btwn 15-
20 kt with higher gusts at times.

&&

.MARINE...
Issued at 207 PM AST Sun Mar 29 2026

A surface trough north of the region will maintain moderate to
locally fresh northeasterly winds across the local waters through
Monday, promoting choppy seas. An approaching frontal boundary
from the western Atlantic will interact with available moisture,
leading to increasing shower activity, particularly from late
Monday into Tuesday. A long-period northerly swell combined with
strengthening winds will result in deteriorating marine conditions
beginning late Monday night and continuing through much of the
Spring Break week. Hazardous seas are expected, with conditions
becoming dangerous for small craft operators.

&&

.BEACH FORECAST...
Issued at 207 PM AST Sun Mar 29 2026

A moderate risk of rip currents is expected along north-facing
beaches of Puerto Rico and the U.S. Virgin Islands, while a low
risk will persist along south-facing beaches.

Conditions are expected to worsen from Monday evening through
Friday due to the arrival of a long-period northerly swell
combined with breezy to windy trade winds. This combination is
likely to create life-threatening rip currents and dangerous high-
surf conditions along the north-facing exposed coastlines.

Beachgoers should exercise caution and remain aware of changing
marine conditions. Always swim near a lifeguard and follow local
safety guidance.

&&

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

$$

SHORT TERM...CAM
LONG TERM....ERG
AVIATION...MMC

NWS SJU Office Area Forecast Discussion