National Weather Service Today's Weather Impact Levels

437
FXCA62 TJSJ 280825
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
425 AM AST Wed Jan 28 2026

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

.KEY MESSAGES...
Issued at 422 AM AST Wed Jan 28 2026

* Relatively stable weather conditions is expected through Friday,
  with brief morning showers in eastern areas of Puerto Rico and
  USVI and afternoon showers developing over western Puerto Rico;
  minor ponding on roads is possible.

* An approaching frontal boundary could bring increasing showers and
  thunderstorms this weekend into early next week, accompanied by
  lightning and gusty winds. Flooding threats may increase from
  limited to elevated, including urban and small stream flooding,
  especially in areas where heavy rainfall persists.

* For the U.S. Virgin Islands, the potential for heavy rainfall and
  thunderstorms appears lower this weekend into early next week, as
  the most active weather is currently expected to remain west of
  the islands. However, passing showers and isolated thunderstorms
  are still possible.

* Marine and coastal conditions may become hazardous by early next
  week, with increasing winds and building seas affecting small
  craft, along with an elevated rip current risk along north-
  facing beaches, creating dangerous swimming conditions at
  exposed locations.

&&

.Short Term(Today through Friday)...
Issued at 422 AM AST Wed Jan 28 2026

Overnight, relatively calm conditions and mostly clear skies
prevailed across the region. Consequently, cool temperatures were
observed across Puerto Rico and the U.S. Virgin Islands, with
minimums ranging from the upper 60s to low 70s in lower elevations
and the upper 50s to low 60s across the higher mountains of Puerto
Rico. Passing showers were noted primarily over the Anegada Passage,
west of St. Croix, and south of Vieques.

Today, local weather will be influenced by surface high pressure
over the central Atlantic and a mid-to-upper-level ridge,
maintaining stable and relatively dry conditions aloft. However, a
patch of low-level moisture carried by the trade winds will filter
into the area, bringing rounds of morning showers to the U.S. Virgin
Islands and portions of eastern and northern Puerto Rico, including
the San Juan metro area. By this afternoon, activity will shift
toward western and northwestern Puerto Rico, driven by daytime
heating and orographic effects. Streamer activity is also possible
from El Yunque toward the San Juan metro area, potentially resulting
in additional afternoon showers. While precipitable water values
will start below the climatological normal at 1.30 inches, they are
expected to rise to an above-normal 1.75 inches by the afternoon.
This setup poses a limited flooding risk, primarily involving
ponding on roads and in areas with poor drainage.

A similar pattern is expected Thursday and Friday, with drier air
filtering in during the early morning followed by another
disturbance that will trigger showers from mid-morning onward.
Conditions will become increasingly unstable late Friday into
Saturday as moisture from a frontal boundary and tropical moisture
from the Caribbean approach the region.

Throughout the short term, temperatures at the 925 mb level will
remain slightly above climatological normals. Maximum temperatures
are forecast to reach the mid-80s in lower elevations and the mid-to-
upper 70s across the higher terrain.

&&

.Long Term(Saturday through Wednesday)...
Issued at 422 AM AST Wed Jan 28 2026

The synoptic pattern is forecast to remain generally unchanged
through the long-term period, with a frontal boundary lingering near
the local area. A southerly to southeasterly low-level flow ahead of
this boundary will persist, continuing to advect warm and moist air
across Puerto Rico and the U.S. Virgin Islands. As a result, above-
normal temperatures are expected to persist through the period.

Global model guidance continues to indicate an increase in available
moisture beginning Saturday, with precipitable water values rising
to near 2.0 inches or higher and remaining above climatological
normals through early next week. Low- to mid-level moisture,
particularly below 700 mb, is forecast to remain elevated. Although
some drying at mid levels (around 700-500 mb) is suggested at times,
the overall moisture profile should remain sufficient to support
periods of enhanced shower and thunderstorm activity.

At upper levels, the region is expected to remain between an upper-
level trough over the western Atlantic and a ridge to the southeast,
providing periods of favorable upper-level dynamics depending on the
exact placement and evolution of these features. This pattern,
combined with persistent low-level moisture convergence along the
nearby frontal boundary, will support increasing rainfall coverage,
particularly from Sunday through Tuesday.

Recent guidance continues to suggest a signal for above-normal
rainfall across portions of the forecast area early next week. Of
note, ECMWF Extreme Forecast Index output consistently highlights a
rainfall signal several days in advance, which is somewhat
surprising given the lead time and suggests increasing ensemble
agreement toward a wetter-than-normal pattern. While confidence in
the exact timing, magnitude, and spatial distribution of rainfall
remains limited at this range, the persistence of the signal
supports a continued potential for locally heavy rainfall,
especially where showers and thunderstorms repeatedly affect the
same areas. Some uncertainty remains with respect to the exact
placement of the frontal boundary, as a westward position closer to
Hispaniola would result in reduced low-level convergence and
consequently less widespread shower and thunderstorm coverage across
the local forecast area.

Diurnal heating, local effects, and sea breeze convergence will
continue to play a role in convective development each afternoon,
depending on the persistence of cloud cover, mainly across interior
and western to northwestern Puerto Rico. Potential impacts include
ponding of water on roadways, urban and small stream flooding, and
localized flooding, particularly in areas that receive repeated
rounds of rainfall. Gusty winds may accompany heavier showers or
isolated thunderstorms.

Overall, the long-term period is expected to remain unsettled, with
the primary concerns being above-normal rainfall and localized
flooding potential through at least Tuesday.

&&

.AVIATION...
(06Z TAFS)
Issued at 422 AM AST Wed Jan 28 2026

Mainly VFR conditions expected to prevail across all TAF sites
during the next 24 hrs. A patch of low-level moisture surge will
increase SHRA aft 28/14Z across eastern PR and the USVI. Later this
afternoon SHRA will develop along central PR and spreading toward
the northwest portions of PR, affecting TJBQ aft 28/17Z. Periods of
reduced VIS and low ceilings can be expected with the strongest
activity. East winds will prevail from 10-15 kt with stronger gusts
and sea breeze variations aft 28/13-14Z.

&&

.MARINE...
Issued at 422 AM AST Wed Jan 28 2026

Light to moderate easterly winds will prevail through the end of the
week as surface high pressure shifts eastward, with seas generally
subsiding across the local waters. By early next week, a
northwesterly to northerly long-period swell is expected to reach
the regional waters by Monday, combining with increasing winds to
produce choppy to rough seas and potentially hazardous marine
conditions, including Small Craft Advisory criteria, particularly
across the offshore Atlantic waters and passages. An increase in
shower and thunderstorm activity is also expected from this
weekend into early next week, especially over the northwestern
Atlantic waters and the Mona Passage, with lightning and gusty
winds possible.

&&

.BEACH FORECAST...
Issued at 422 AM AST Wed Jan 28 2026

A series of weak northerly swells will continue to reach the
Atlantic waters through the week and into the weekend, maintaining a
moderate rip current risk along most north-facing beaches of the
islands, where life-threatening rip currents are possible. Localized
areas of high rip current risk cannot be ruled out, particularly
along the most exposed beaches during periods of higher swell energy.

Beach conditions may further deteriorate by early next week due to
increasing winds and the arrival of a northwesterly to northerly
long-period swell, which could result in more hazardous surf
conditions. In addition, showers and thunderstorms, especially from
this weekend into early next week, may produce gusty winds,
lightning, and rapidly changing conditions, increasing the risk for
beachgoers.

For localized and updated rip current information, visit
weather.gov/beach/sju.

&&

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

$$

SHORT TERM/AVIATION...GRS
LONG TERM/MARINE/BEACH...CVB

NWS SJU Office Area Forecast Discussion