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215
FXCA62 TJSJ 260730
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
330 AM AST Fri Jun 26 2026

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

.KEY MESSAGES...
Issued at 329 AM AST Fri Jun 26 2026

* High concentrations of Saharan Dust will persist through late this
  afternoon over the region, becoming moderate tonight and low early
  tomorrow.

* Hazy skies, reduced visibility, limited afternoon convection and
  deteriorated air quality will continue today.

* Breezy ENE winds will result in a moderate rip current risk and
  locally choppy seas; as winds become lighter marine and beach
  conditions will improve tonight and into the weekend.

* An upper-level low will induce a surface trough that will cross
  the islands tomorrow, promoting lighter winds as well as a
  limited flooding and lightning risk.

&&

.Short Term(Today through Sunday)...
Issued at 329 AM AST Fri Jun 26 2026

A Saharan Air Layer (SAL) is moving over the region and will
continue to dominate today`s weather pattern. These Saharan Dust
particulates will result in hazy skies, reduced visibility and
deteriorated air quality. Individuals in sensitive groups (such as
those with respiratory conditions, young children, and older
adults) should take appropriate precautions and limit prolonged
outdoor exposure today. Generally warm 500 mb temperatures will
also persist throughout most of the period. Precipitable water
(PWAT) values today will be below normal to low-end normal values.
The prevailing dry air mass will generally suppress shower
development, though local effects could trigger a few afternoon
showers across the interior and western and southwestern portions
of Puerto Rico as up to breezy steering flow backs today to become
more E to ENE. Widespread rain is not expected today. High
concentrations of Saharan Dust will persist through late this
afternoon over the region, with conditions gradually improving
over the USVI first and then gradually over PR as the SAL
continues moving westward, generally moderate concentrations are
expected tonight. By Saturday, air quality will have improved as
the SAL is forecast to have already exited the area. An upper-
level low is forecast to induce a surface trough that will move
across the region on Saturday. As this surface trough nears the
northeastern Caribbean, PWAT values will return to more normal
values and reach around 1.8 inches (locally higher). This shift in
the pattern will bring morning showers to eastern and windward
regions, followed by afternoon showers and isolated thunderstorms
over interior to W and NW Puerto Rico as winds veer with the
passage of the surface trough and become more E to ESE. Lines of
showers can also develop from the USVI and El Yunque. Due to
lighter steering winds, these slower moving showers can lead to a
limited flooding and lightning risk. Drier conditions will return
Sunday following the disturbance, with precipitable water values
forecast at below normal values. High pressure over the eastern
Atlantic will promote a breezy E to ESE flow, also steering low
concentrations of Saharan dust towards the islands. Windward
showers and afternoon convection over interior to W-NW PR continue
to be forecast. PWAT values will then start to climb late Sunday
night as the moisture field from a tropical wave approaches. An
elevated heat risk will persist during the period, although the
drier air today and Sunday can serve to limit heat indices. 925 mb
temperatures are forecast at normal values today and above normal
on Saturday and Sunday.

&&

.Long Term(Monday through Friday)...
Issued at 329 AM AST Fri Jun 26 2026

During the long-term period, a surface high pressure over the
eastern Atlantic will maintain a southeasterly low-level flow across
the region through the workweek. By Monday into Tuesday, current
guidance continues to suggest that moisture associated with a
tropical wave will approach the Caribbean Basin, resulting in a
gradual increase in deep-layer moisture across the local islands. As
a result, precipitable water (PWAT) values should increase to near-
normal or slightly above-normal levels, ranging from around 1.7 to
nearly 2.0 inches based on climatological averages. In addition,
relative humidity within the 700-500 mb layer is forecast to rise to
near or above seasonal values. This increase in moisture should
enhance rainfall potential, resulting in greater coverage of showers
and afternoon convection, with localized ponding of water possible
on roads and in poorly drained areas. Cooler temperatures aloft
associated with lower 500 mb temperatures may also provide
additional support for convective development during the afternoon
hours. However, lingering low to moderate concentrations of Saharan
dust may limit convective coverage to some extent, introducing
uncertainty in the overall coverage and intensity of rainfall. Also,
low to slightly moderate concentrations of Saharan Dust is expected
to remain present, and its interaction with the incoming moisture
introduces some uncertainty to the forecast. By mid week into the
end of the week; particularly Thursday and Friday, drier air is
expected to filter into the region (PWAT below 1.5 inches), leading
to a gradual decrease in rain chances.

One of the primary weather concerns throughout the period will be
the persistence of warm to hot conditions. Forecast guidance
indicates 925 mb temperatures around two standard deviations above
normal, particularly on Monday, when the combination of above-normal
temperatures and increasing moisture will promote hot and muggy
conditions. Daytime high temperatures are expected to reach the
upper 80s to lower 90s, with heat index values potentially exceeding
100 degrees F, especially across coastal and urban areas. As a
result, an elevated heat risk is likely to persist through much of
the forecast period. Residents and visitors are encouraged to stay
hydrated, wear lightweight and loose-fitting clothing, and take
frequent breaks in shaded or air-conditioned areas if spending
extended periods outdoors.

&&

.AVIATION...
(06Z TAFS)
Issued at 329 AM AST Fri Jun 26 2026

Mainly VFR conditions, although HZ will continue today, reduce
visibilities to around 6 SM and promote occasional MVFR conditions.
HZ decreasing this evening to tonight. Passing -SHRA/VCSH across
windward sectors at times. E to ENE winds increasing after 25/14z to
10-20 kt, with higher gusts and sea breeze variations; winds
decreasing after 26/23Z to 5-12 kt, with occasional higher gusts and
land breezes.
&&

.MARINE...
Issued at 329 AM AST Fri Jun 26 2026

A broad surface high pressure system over the Atlantic will maintain
moderate to locally fresh easterly winds across the regional waters
today. Thus, choppy seas and Small Craft Exercise Caution conditions
will persist across portions of the local waters today, before
gradually improving over the weekend and into early next week as
winds diminish and become more east-southeast. A surface trough is
expected to increase shower activity and the potential for isolated
thunderstorms across the regional waters around Saturday. Moderate
concentrations of Saharan dust will continue through this evening.

&&

.BEACH FORECAST...
Issued at 329 AM AST Fri Jun 26 2026

Moderate easterly winds will continue to support a moderate risk of
life-threatening rip currents along many beaches of Puerto Rico,
Culebra, Vieques, and St. Croix today. A moderate risk will persist
for the beaches of St. Croix and Culebra on Saturday, and for
northwestern Puerto Rico as well on Sunday. Elsewhere, the rip
current risk will gradually diminish to low as winds weaken across
the region. However, even when the risk is low, isolated life-
threatening rip currents can still occur, especially near jetties,
groins, reefs, and piers. Beachgoers should swim near lifeguards
whenever possible, heed beach warning flags, and follow the advice
of local beach patrols.

&&

.FIRE WEATHER...
Issued at 329 AM AST Fri Jun 26 2026

A Fire Danger Statement has been issued for today (from 10 AM to 4
PM AST) across portions of the southern coastal plains of Puerto
Rico due to the combination of critically dry fuels, high KBDI
values, sustained winds of 15 to 20 mph with gusts up to 30 mph, and
possible minimum relative humidity values in the 40s to low 50s as
dry air with high concentrations of Saharan Dust continue moving
over the region. Prolonged rainfall deficits, abnormally dry to
severe drought conditions, and critically dry fuels also continue.
These conditions will favor rapid wildfire ignition and extreme fire
behavior, meaning any fires that develop will likely spread quickly
and become difficult to contain. Outdoor burning is highly
discouraged. With more E-NE steering flow, shallow afternoon
convection could provide some relief to the SW coastal plains
today.

&&

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

$$

KEY MESSAGES...MRR
SHORT TERM...MRR
LONG TERM....YZR
AVIATION...MRR
MARINE...CAM
BEACH FORECAST...CAM
FIRE WEATHER...MRR

NWS SJU Office Area Forecast Discussion