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718
FXCA62 TJSJ 080616
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
216 AM AST Sat Aug 8 2026

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

.KEY MESSAGES...
Issued at 157 AM AST Sat Aug 8 2026

- Heat Advisory for Puerto Rico and the US Virgin Islands as we
  forecast hot conditions today. This warm weather pattern should
  prevail through the end of the weekend, particularly over urban
  and low lying areas.

- Elevated fire weather conditions may persist for the next few
  days across southern and southwestern Puerto Rico due to
  critically dry fuels, low relative humidity, and breezy
  conditions.

- Moderate concentrations of Saharan Dust will reach the local
  area today, with very high concentrations on Sunday and Monday.
  Sensitive groups must follow medical recommendations.

- A drier and more stable weather pattern will persist through the
  weekend. Limited rainfall is expected, allowing drought
  conditions to continue worsening across Puerto Rico and the U.S.
  Virgin Islands.

&&

.Short Term(Today through Monday)...
Issued at 157 AM AST Sat Aug 8 2026

Similar to previous nights, generally calm weather prevailed
overnight, with mostly clear skies across Puerto Rico and the
U.S. Virgin Islands. Winds were light and mainly easterly, while
temperatures ranged from the upper 70s to lower 80s along the
coast and remained in the 70s across the interior and higher
areas. Light concentrations of Saharan dust gradually reached the
U.S. Virgin Islands and eastern Puerto Rico overnight.

Today, dry, warm and stable conditions will accompany the arrival
of a dense Saharan Air Layer. The latest model guidance suggest
precipitable water values falling well below normal for this time
of the year along with RH at mid- levels suppressing shower
development. Therefore, mostly fair weather with increasingly hazy
skies and limited rainfall is expected across Puerto Rico and the
U.S. Virgin Islands. A Heat Advisory was issued for the
coastal and urban areas of Puerto Rico and the US Virgin Islands,
this will be in effect from 10 AM through 5 PM today.

The Saharan dust event is expected to peak on Sunday, with dust
aerosol guidance indicating high concentrations across the region.
A weak tropical wave mainly south of the islands will bring some
moisture back into the area. However, the dry and stable air
associated with the Saharan Air Layer should limit the development
of any significant rainfall. By Monday, dust concentrations
should gradually decrease as deeper tropical moisture returns,
allowing a more typical pattern of passing windward showers and
afternoon convection across western Puerto Rico.

Heat, haze, and poor air quality will be the main impacts through
the weekend. Abundant sunshine will promote rapid daytime heating,
while the dense dust layer may limit overnight cooling and allow
each day to begin with already warm temperatures. As tropical
moisture increases, the combination of heat and humidity will make
conditions uncomfortable. Meanwhile, high dust concentrations,
particularly on Sunday, will reduce air quality and could
aggravate respiratory conditions. Residents and visitors,
especially those sensitive to poor air quality and excessive heat,
should limit prolonged outdoor exposure, stay hydrated, and take
frequent breaks in shaded or air-conditioned areas.

&&

.Long Term(Tuesday through Saturday)...
Issued at 157 AM AST Sat Aug 8 2026

Weather conditions during the long-term period will turn more
variable with the arrival of a wind surge and a tropical wave across
the CWA. On Tuesday, a surface high pressure anchored over the
Central Atlantic will maintain easterly winds, pushing a weak wind
surge in the 700 to 500 mb layer across the area. Precipitable water
values are forecast by the GFS and ECMWF to range between 1.6 and
1.8 inches, which will be enough moisture to enhance afternoon
convection along the western sections of the islands. From late
Tuesday into Wednesday, surface winds will shift more from the
southeast due to the interaction between the Atlantic surface high
and the approaching tropical wave. The peak of this moisture field
is forecast for Wednesday afternoon, favoring a variable weather
pattern with morning to early afternoon showers along northeastern
Puerto Rico, followed by deep afternoon convection along the western
coast driven by local effects. Although rainfall accumulations of 1
to 2 inches are possible with the heaviest showers, this will not be
enough to mitigate existing drought conditions across the island.

A rapid drying trend is forecast by Thursday as a drier air mass
moves back into the region, limiting overall shower development
across the area. By Friday, global model guidance suggests another
tropical wave tracking across the Caribbean region. As of today, the
GFS keeps the bulk of the moisture moving over the Caribbean waters
south of the local area. However, given the extended time frame
of the forecast, changes to the moisture track and intensity
remain possible by the end of the period.

&&

.AVIATION...
(06Z TAFS)
Issued at 157 AM AST Sat Aug 8 2026

Mostly VFR conditions across all TAF sites. Moderate
concentrations of HZ will prevail across all terminal from 08/12Z
onwards. Brief periods of MVFR condt possible due to VCTS near
TJBQ and TJPS from 08/17Z trough 08/23Z. Winds will remain from
the E around 15 kts and occasional higher gusts.

&&

.MARINE...
Issued at 157 AM AST Sat Aug 8 2026

A broad surface high over the Atlantic will maintain moderate to
fresh easterly winds tonight, with winds strengthening through the
weekend. Marine conditions will become increasingly choppy, with the
highest risk for hazardous conditions Sunday into Monday,
particularly across the offshore waters and local passages.
Afternoon thunderstorms may produce locally hazardous winds and
seas, while Saharan dust may reduce visibility through the weekend.

&&

.BEACH FORECAST...
Issued at 157 AM AST Sat Aug 8 2026

A moderate risk of rip currents will continue along the north- and
east- to southeast-facing beaches of Puerto Rico into early next
week. The risk should decrease to low across most beaches by
midweek, before increasing to moderate Thursday and potentially high
Friday into next weekend as easterly winds strengthen significantly.

Heat will remain the primary beach hazard this weekend, while
isolated afternoon thunderstorms over western Puerto Rico may
produce dangerous cloud-to-water lightning. A dense Saharan dust
plume will arrive Saturday morning, peaking Saturday evening into
Sunday, with reduced visibility and hazy conditions expected.

&&

.FIRE WEATHER...
Issued at 157 AM AST Sat Aug 8 2026

Critical fuel conditions persist across the islands, with extreme
drought conditions across portions of the southern coastal plains of
Puerto Rico. As a drier air mass continues to filter into the
region, moisture content will drop significantly, with RH values
between 47 and 50 percent, well below thresholds. Due to critical
fuel conditions across the southern area of the island and KDBI
values well above thresholds, the fire danger threat remains
ELEVATED. Therefore, a Fire Danger Statement is in effect from 10
AM through 5 PM AST. Residents and visitors are encouraged to
avoid outdoor burning, as conditions will likely be favorable for
wildfire ignition and rapid spread.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for PRZ001>005-007-008-010>013.

VI...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
     for VIZ001-002.

AM...None.
&&

$$

SHORT TERM/AVIATION/FIRE WEATHER...MMC
LONG TERM...LIS
MARINE/BEACH FORECAST...MMC

NWS SJU Office Area Forecast Discussion