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

913
FXCA62 TJSJ 030713
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
313 AM AST Tue Nov 3 2026

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

.KEY MESSAGES...
Issued at 257 AM AST Tue Nov 3 2026

- Hot and humid conditions will lead to increasing heat indices
  and with it the risk of heat related illnesses, especially for
  those spending extended periods outdoors. Therefore, a Heat
  Advisory will be in effect from 9 AM through 2 PM today.

- Expect afternoon showers and thunderstorms to develop over
  western and northwestern Puerto Rico. Ponding of water over
  roads and poorly drained areas remains possible for today.

- Slow-moving showers and thunderstorms Thursday through Saturday
  may produce urban and small-stream flooding, with isolated flash
  flooding possible, particularly across northern and interior
  Puerto Rico.

- Weather conditions will improve from Sunday into early next
  week, although afternoon showers remain possible.

- Choppy marine conditions will gradually improve through midweek
  as winds and seas diminish. The risk of rip currents will also
  decrease across many beaches. However, another swell arriving
  late in the week could bring hazardous surf and rip current
  conditions during the weekend, particularly along the northern
  coast of Puerto Rico and the northern U.S. Virgin Islands. Refer
  to the Beach Forecast section for additional details.

&&

.Short Term(Today through Thursday)...
Issued at 257 AM AST Tue Nov 3 2026

Generally calm weather conditions prevailed across Puerto Rico and
the US Virgin Islands overnight, with mostly clear skies across
Puerto Rico and isolated to scattered showers affecting the
surrounding waters and portions of the US Virgin Islands, although
rainfall accumulations remained minimal. Temperatures dropped
into the 70s along coastal areas of Puerto Rico and into the 60s
across higher elevations, while the US Virgin Islands remained in
the upper 70s to lower 80s under partly cloudy skies. Winds were
generally light.

For today, above-normal temperatures, abundant surface moisture, and
a prevailing southerly wind component will favor elevated heat
indices across Puerto Rico and the US Virgin Islands for the first
half of the day. Following several days of temperatures reaching
the lower 90s, mostly clear skies overnight and through the
morning hours will allow rapid daytime heating, with heat indices
approaching 108 degrees Fahrenheit or briefly higher, particularly
across coastal and urban areas. Given these conditions, the first
Heat Advisory of November has been issued from 9 AM to 2 PM AST.
Increasing cloud cover and afternoon showers and thunderstorms
should provide some relief from the heat later in the day.
Residents and visitors are urged to stay hydrated, limit strenuous
outdoor activities, and seek shade or air-conditioned
environments when possible.

Aside from the heat, east-southeasterly winds, combined with daytime
heating and local effects, will favor afternoon showers and
thunderstorms across the western interior and northwestern
portions of Puerto Rico, where the highest rainfall accumulations
are anticipated. Although localized ponding of water and lightning
will remain possible, widespread flooding is not anticipated
today.

Looking ahead through Thursday, the latest model guidance suggests
a gradual increase in atmospheric moisture and instability, with
precipitable water values reaching 2.0 to 2.3 inches and the
greatest potential for convective activity expected late Thursday.
As a frontal boundary remains just north of the region, winds will
gradually shift to southerly by midweek and west-southwesterly on
Thursday, shifting the focus of afternoon convection toward the
northern half of Puerto Rico. Additionally, weakening winds may
allow showers and thunderstorms to linger over the same locations,
increasing rainfall accumulations and lightning threats. By
Thursday, deeper moisture and slow-moving convection will increase
the potential for urban and small-stream flooding, with a low
chance of isolated flash flooding. Saharan dust concentrations are
expected to remain low through the end of the workweek.

&&

.Long Term(Friday through Tuesday)...
Issued at 257 AM AST Tue Nov 3 2026

For Friday through Saturday, atmospheric instability is expected to
remain elevated. Precipitable water (PWAT) values will continue
above normal (between 2 to 2.3 inches) through at least Sunday.
Relative humidity (RH) in the 850700 mb layer will stay high while
mid-level moisture (700500 mb) is set to increase to 80% through
early Saturday.  An upper-level trough, along with its corresponding
surface low and frontal boundary, will track northward across the
Atlantic. Although the core of maximum instability is expected to
pass north of the area, this will set up a southwesterly to westerly
(light to variable) steering flow, drawing tropical moisture
northward into our area. This steering flow will be generally light
and variable. Consequently, slow-moving showers are likely to
develop, generating elevated rainfall totals, primarily across the
southern, interior, northern and northeastern sectors of Puerto
Rico, as well as the U.S. Virgin Islands. This will result in
flooding (Risk level 2 of 4) especially across interior, northern
and northeastern Puerto Rico during the afternoon hours. Although
model guidance continues to indicate mid to upper level ridging
building over the islands to start the next week, prompting a more
stable pattern. Model discrepancies continue through Tuesday. The
GFS preserves higher moisture availability throughout the
atmospheric column, specifically within PWAT, 850700 mb RH and 700-
500 mb RH. Conversely, the ECMWF projects a drier 850-500 RH profile
alongside reduced PWAT values. Uncertainty continues to be present
concerning the overall moisture content. While daytime heating and
local effects can trigger isolated to scattered afternoon showers
across the islands, an overall reduction in rainfall coverage and
intensity is anticipated, thereby lowering the risk of flooding.
Steering flow Sunday through Tuesday is forecast to be generally
light to variable from the southwest before gradually backing and
becoming more southerly as the period continues. Please monitor
future updates as changes to the forecast are possible.

&&

.AVIATION...
(06Z TAFS)
Issued at 257 AM AST Tue Nov 3 2026

All TAF sites should experience VFR conditions. However, brief
period of MVFR conds possible with SHRA and TS, occasionally
reaching TJBQ and TJSJ after 03/17Z. Winds will become SE around
10-15 kts, with stronger gusts near the heaviest thunderstorms
activity. Winds will become lighter (3 to 5 knots) by 03/23Z.
Expect VCSH over TIST and TISX after 04/00Z.

&&

.MARINE...
Issued at 257 AM AST Tue Nov 3 2026

A weakening Atlantic ridge will initially maintain light to moderate
east to southeast winds. Winds will gradually become southerly as a
frontal boundary approaches from the northwest and a weak surface
low develops north of Puerto Rico by Thursday. The weakening
pressure gradient will favor light, variable winds, with subsequent
wind shifts depending on the low`s evolution. Seas will generally
subside through midweek before a northerly swell arrives Friday into
the weekend, building seas across the Atlantic waters and exposed
passages.

&&

.BEACH FORECAST...
Issued at 257 AM AST Tue Nov 3 2026

A moderate risk of rip currents will persist along portions of the
north- and east-facing beaches of Puerto Rico and the northern US
Virgin Islands through midweek, including portions of St. Croix
today. A northerly swell arriving Friday into the weekend will
increase surf and maintain a moderate rip current risk along the
northern US Virgin Islands and northern Puerto Rico, expanding to
western beaches by Saturday. Elsewhere, the risk will generally
remain low, although isolated stronger rip currents are still
possible near piers, jetties, and channels. Isolated thunderstorms
could also pose a lightning threat to beachgoers, particularly
across Puerto Rico, Vieques, and Culebra each afternoon. Seek
shelter indoors if thunder is heard.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 9 AM this morning to 2 PM AST this afternoon
     for PRZ001>013.

VI...Heat Advisory from 9 AM this morning to 2 PM AST this afternoon
     for VIZ001-002.

AM...None.
&&

$$

SHORT TERM/AVIATION...MMC
LONG TERM...MRR
MARINE/BEACH FORECAST...CAM

NWS SJU Office Area Forecast Discussion