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676
FXCA62 TJSJ 241847
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
247 PM AST Mon Aug 24 2026

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

.KEY MESSAGES...
Issued at 247 PM AST Mon Aug 24 2026

- Heat remains the primary threat, with warm to hot conditions
  persisting this week along urban and low-lying areas of the
  islands. Stay hydrated.

- Frequency of showers and isolated thunderstorms will likely
  increase late tonight into Tuesday, leading to ponding of water
  over roadways and poorly drained areas, including minor
  flooding.

- Moderate to high concentrations of Saharan Dust are expected
  to increase Tuesday night, peaking on Wednesday, bringing hazy
  skies, reduced visibility, and poor air quality.

- The low risk of rip currents continues across the islands, becoming
  moderate by the second part of the workweek.

&&

.Short Term(This evening through Wednesday)...
Issued at 247 PM AST Mon Aug 24 2026

Earlier today, passing showers were observed across the windward
areas of Puerto Rico. Around midday, a streamer developed, leaving
around 1 to 1.5 inches of rainfall based on radar estimates,
particularly across Bayamon and Guaynabo. Showers and
thunderstorms then developed across the interior and western
portions of Puerto Rico. A Special Weather Statement was issued
due to wind gusts of up to 40 mph and frequent lightning. A few
Flood Advisories were also issued. Daytime maximum temperatures
ranged from the upper 80s to low 90s across coastal and urban
areas, and from the low 80s across higher-elevation areas.

The forecast remains on track for another tropical wave to move
over the region on Tuesday, which is forecast to be the day with
greater rain chances of the short-term period. Precipitable Water
values (PWAT) will increase to around the 75th percentile, near 2
inches or higher, along with an increase in 850 to 500 mb
relative humidity. Expect the frequency of showers to increase
tomorrow morning across eastern areas of Puerto Rico and the U.S.
Virgin Islands, followed by the formation of streamers from El
Yunque into the metropolitan area and afternoon convection over
interior and western Puerto Rico, which could lead to flooding in
urban, low-lying, and poor drainage areas. Although an increase
in rainfall activity is expected, forecast rainfall accumulations
will likely not be enough to significantly improve the ongoing
drought conditions across the affected areas.

By late Tuesday night into Wednesday, moderate to high concentrations
of Saharan dust particles are forecast to filter into the region.
A surface high pressure over the central to eastern Atlantic will
slightly shift more to the east, causing winds to shift back to a
more easterly direction across the region. Overall, expect hazy
skies and a seasonal weather pattern across the islands, with
afternoon convection mainly driven by local and sea-breeze
effects. A weak upper-level low will linger near the region,
leading to cooler 500-mb temperatures that will likely favor the
development of thunderstorms.

Additionally, a persistent threat for the remainder of the short-
term period will be an elevated to significant heat threat. The
issuance of heat product alerts will likely be needed in the
coming days. Residents and visitors are encouraged to remain
hydrated to help limit the effects of the heat.

&&

.Long Term(Thursday through Monday)...
Issued at 320 AM AST Mon Aug 24 2026

A surface high pressure system over the central
Atlantic will dominate local weather conditions through much of the
period, driving mostly east-southeasterly winds across the
northeastern Caribbean. A mid-level ridge aloft will further
reinforce dry, stable air.

Drier-than-normal conditions are expected to prevail Thursday and
Friday, with precipitable water (PWAT) values remaining below the
climatological normal of 1.25 inches. Nevertheless, passing patches
of moisture will bring brief, fast-moving showers to the region.
Afternoon convection driven by daytime heating and localized effects
may trigger showers and a few isolated thunderstorms over western
Puerto Rico.

From Friday night into Saturday, the latest model guidance suggests
a tropical wave will approach the area. However, the bulk of its
moisture is expected to remain over the Caribbean Sea, with only the
northern periphery reaching the region to bring PWAT values up to
1.751.90 inches. Because some uncertainty remains, residents and
local interests should continue monitoring forecast updates as this
wave evolves.

PWAT values will drop rapidly following the wave`s passage, re-
establishing dry, stable air and limiting rainfall chances through
early next week. Meanwhile, warmer-than-normal temperatures will
persist throughout the forecast period. Model guidance shows 925 mb
temperatures running nearly two standard deviations above average
for this time of year. Combined with southeasterly winds, seasonal
moisture, and Saharan dust, these conditions may warrant heat
advisories or warnings by the end of the week.

&&

.AVIATION...
(18Z TAFS)
Issued at 247 PM AST Mon Aug 24 2026

Mainly VFR conds expected across all terminals thru the forecast
period. SHRA/TSRA development over W PR may result in intermittent
MVFR conds at/near TJBQ betw 24/19Z-23Z. E-ESE winds 10-15 kts
with some periods of higher gusts, becoming lighter overnight,
increasing again aft 24/13Z. The frequency of VCTS/TSRA/SHRA may
increase Tuesday as a tropical wave moves across the region.

&&

.MARINE...
Issued at 247 PM AST Mon Aug 24 2026

A surface high pressure over the western Atlantic is expected to
build and extend into the central Atlantic, promoting moderate east-
southeasterly winds across the area, becoming moderate to locally
fresh from time to time. Under this pattern, seas will generally
remain between 3 and 4 feet, occasionally 5 feet, across the
regional waters for the next few days. A tropical wave is forecast
to approach the eastern Caribbean on Tuesday, bringing enhanced
shower and thunderstorm activity across the local waters and
passages. Saharan dust concentrations should gradually increase on
Tuesday night, peaking on Wednesday, bringing hazy skies and
slightly reduced visibility. A weak long-period swell should arrive
and spread across the regional waters by Thursday.

&&

.BEACH FORECAST...
Issued at 247 PM AST Mon Aug 24 2026

The beach forecast remains on track, as the low risk of rip currents
continues across the islands. The latest nearshore buoys continue to
report seas between 2 and 3 feet, while winds remain between 15 and
20 kts, with gusts up to 25 kts. Therefore, the risk will remain low
for the rest of today, though beachgoers should always pay attention
to the beach conditions, as life-threatening rip currents can often
occur near groins, jetties, piers, and reefs. These conditions
should continue through midweek, becoming moderate for the second
part of the workweek and upcoming weekend. A weak long-period swell
may arrive and spread across the regional waters by Thursday;
breaking waves should remain between 3 and 5 feet, but the risk
should remain moderate. Aside from rip currents, residents and
visitors should remain weather alert as tropical waves moving across
the CWA will enhance shower and thunderstorm activity near coastal
areas of the islands. Isolated thunderstorms could produce gusty
winds and lightning, and beachgoers should seek shelter whenever
they hear thunder.

&&

.FIRE WEATHER...
Issued at 247 PM AST Mon Aug 24 2026

Around mid-morning, surface stations showed minimum RH values
near 55% in Guanica, but values overall remained in the upper 60s
or higher across most areas of southern Puerto Rico and the U.S.
Virgin Islands. Available moisture across the region from a
departing weak tropical wave and local effects are resulting in
afternoon showers, which are keeping RH values above critical
thresholds through the remainder of the afternoon. As a result,
the fire weather risk remains low for the rest of today.

In terms of surface winds, a more east-southeasterly wind pattern
is forecast to continue. The arrival of a tropical wave tomorrow,
Tuesday, will reduce the fire weather risk and keep it low.
However, stressed vegetation and dry fuels are still present,
particularly across the southern plains and hills of Puerto Rico
and the U.S. Virgin Islands. Residents and visitors are urged to
avoid outdoor burning, as conditions could easily support wildfire
ignition and rapid spread.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory until 4 PM AST this afternoon for PRZ001>003-005-
     007-008-010>013.

VI...Heat Advisory until 4 PM AST this afternoon for VIZ001-002.

AM...None.
&&

$$

SHORT TERM/AVIATION/FIRE WX...YZR
LONG TERM...GRS
MARINE/BEACH FORECAST...MNG

NWS SJU Office Area Forecast Discussion