National Weather Service Today's Weather Impact Levels

941
FXCA62 TJSJ 110720
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
320 AM AST Wed Mar 11 2026

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

.KEY MESSAGES...
Issued at 302 AM AST Wed Mar 11 2026

* Fresh to locally strong winds will continue to result in choppy
  to rough seas across the offshore Atlantic waters through this
  afternoon. Slight improvement in marine conditions is expected
  starting today through at least Saturday.

* Breezy to locally windy conditions will gradually decrease
  across the islands today and becoming lighter from Thursday
  onward.

* Frequent passing trade wind showers are expected to move across
  the region over the next few days, with afternoon convective
  activity over western Puerto Rico.

* Across the U.S. Virgin Islands, occasional passing trade wind
  showers will continue, with a drying trend expected by Friday.

&&

.Short Term(Today through Friday)...
Issued at 302 AM AST Wed Mar 11 2026

Clear to partly cloudy skies prevailed across Puerto Rico and the
U.S. Virgin Islands overnight. Radar imagery showed bands of showers
moving over Vieques and the eastern and northern portions of Puerto
Rico. Doppler radar estimated rainfall accumulations of up to 0.30
inches in the heaviest areas, particularly between Patillas and
Humacao. While the U.S. Virgin Islands experienced brief showers,
most of the activity remained over the coastal waters. Low
temperatures ranged from the low to mid-70s across coastal and urban
areas, while the higher mountains of Puerto Rico saw lows in the low
to mid-60s. Winds remained light and variable throughout the night.

A broad surface high pressure system over the central Atlantic will
continue to shift eastward through the end of the workweek. In
response, winds will begin to decrease as an induced low-level
trough approaches from the north-northeast. Local weather conditions
are not expected to vary significantly over the next few days, as
alternating patches of moisture and drier air from the tropical
Atlantic move intermittently across the region. This will promote
alternating wet and dry periods, enhanced by an approaching upper-
level trough and its associated low-level feature through at least
Thursday. Precipitable water (PWAT) values through Thursday will
remain above climatological normals, ranging from 1.50 to 1.60
inches. With instability aloft enhanced by the upper-level trough,
500 mb temperatures will drop to between-10C and -11C through
Thursday, supporting deep convective activity during the afternoon
hours across interior and western Puerto Rico.

By Friday and into Saturday, a mid-level ridge is expected to build
across the region, promoting more stable and drier conditions aloft.
This will reduce PWAT values to near 1.00 inch, which is below
climatological normals. Consequently, significant shower activity is
not anticipated over the weekend. However, light passing showers
will continue to affect the windward portions of the islands
periodically during the morning hours.

&&

.Long Term(Saturday through Wednesday)...
Issued at 302 AM AST Wed Mar 11 2026

Current model guidance suggests PWAT values around 1.20 to 1.40
inches on Saturday, increasing to around 1.6 inches on Sunday as a
patch of more humid air approaches the area. Favorable conditions for
shower development will continue as a jet stream aloft continues to
promote ventilation to accompany the low level moisture approaching
the area. This can promote vertical shower development and possible
t-storm formation, particularly during afternoon convection over
interior to southwestern PR on Saturday under ENE flow and interior
to northwestern PR under ESE flow Saturday onwards, as well as lines
of showers from the USVI, Vieques and Culebra to ESE PR. Sunday
appears to be the wettest day of the weekend. A broad surface high
will move into the western Atlantic and continue building, promoting
increased wind speeds. 925 mb wind speeds will be above normal,
resulting in breezy to locally windy conditions to start the next
week. For the first half of the next workweek, more stable
conditions will dominate with warmer 500 mb temperatures. This will
serve to limit shower development, however breezy ESE flow will
steer showers and patches of moisture towards windward sectors with
diurnal heating promoting afternoon convective showers over interior
to northwestern PR, as well as lines of showers towards the local
islands. 925 mb temperatures will remain at normal values but under
a general warming trend with less cloud cover.

&&

.AVIATION...
(06Z TAFS)
Issued at 302 AM AST Wed Mar 11 2026

Mainly VFR conds are expected to prevail across all TAF sites
during the forecast period. However, quick passing trade wind
SHRA may result in VCSH at all terminals 11/23Z causing brief MVFR
cigs, particularly at TJSJ/TJBQ. E winds btwn 15-20 kt with gusts
up to 28 kt and sea breeze variations aft 11/14Z.

&&

.MARINE...
Issued at 302 AM AST Wed Mar 11 2026

A broad surface high pressure system across the offshore Atlantic
will promote moderate to fresh easterly winds, keeping seas 6 to 7
feet across the offshore Atlantic waters through at least this
morning. A Small Craft Advisory will remain in effect for that area
through this morning. Across most nearshore and coastal waters, seas
will remain between 5 and 6 feet, resulting in choppy marine
conditions. Small craft operators are urged to exercise caution.
Subsiding seas to between 3 to 5 feet are forecast tomorrow,
Thursday, and Friday as winds also decrease. Winds are forecast to
increase around Saturday night into early next week, leading to
building seas to around 6 to 8 feet and deteriorated marine
conditions once again.

&&

.BEACH FORECAST...
Issued at 302 AM AST Wed Mar 11 2026

A moderate risk of rip currents (life-threatening rip currents are
possible in the surf zone) for most local beaches. Beachgoers should
continue to exercise caution. Tomorrow and Friday, winds are
expected to subside. However, a moderate risk of rip currents will
continue mainly across north and east-facing beaches of Puerto Rico,
Vieques, Culebra, and St. Croix . A low risk of rip currents will be
present across western and southern exposed beaches of the islands.
Even if the risk is low, life-threatening rip currents often occur
in the vicinity of groins, jetties, reefs, and piers. The risk is
forecast to increase to high around late Sunday into early next
workweek. For additional information, please visit:
weather.gov/beach/sju.

&&

.FIRE WEATHER...
Issued at 302 AM AST Wed Mar 11 2026

The KBDI remains above critical fire weather thresholds in Cabo
Rojo (670) and below thresholds in Guanica (520) and Camp
Santiago (390). Breezy to windy easterly winds will continue
between 13 to 18 mph with higher gusts up to 25 mph at times.
Today, RH values will drop near and below critical levels at times
as a patch of dry air filters into the area by mid-morning.
Passing showers will continue to move across the area from time to
time; however, drying soils, lower humidity later in the day and
and strong winds will maintain a moderate to elevated fire danger
risk today, particularly for southwestern Puerto Rico. By later
today through at least Saturday, winds are expected to become
light to moderate. Additionally, RH values are expected increase
due to the arrival of another patch of moisture into the area. At
this time an RFD will not be issued. We urge partners to continue
monitoring updates during the morning for a possible elevated
fire danger risk if conditions warrant.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory until noon AST today for AMZ711.

&&

$$

SHORT TERM/AVIATION/FIRE WEATHER...GRS
LONG TERM/MARINE/BEACH FORECAST....MRR

NWS SJU Office Area Forecast Discussion