Valid Sunday June 21, 2026 to Saturday June 27, 2026
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM
EDT June 13 2026
Synopsis: Mid-level high pressure is expected to
increase chances for extreme heat from the Central Gulf Coast through Florida
and the South Atlantic Coast into the middle of the period. Then, as conditions
in the southeast ease, mid-level high pressure is expected to build farther
west later week-2, bringing the threat of extreme heat to the South-Central
States, the Desert Southwest, and the California Valleys during the last half
of the period. A surface front along the southern edge of unseasonably cool air
is predicted early week-2 from the east-central Great Plains through much of
the Middle Mississippi, Tennessee, and Ohio Valleys, enhancing chances for
heavy precipitation there.
Hazards - Slight risk of
extreme heat along the Central Gulf and South Atlantic Coasts, and the entire
Florida Peninsula, Sun-Thu, Jun 21-25.
- Slight risk of extreme heat for much of the Central and Southern Plains and
Lower Mississippi Valley, Wed-Sat, Jun 24-27.
- Slight risk of extreme heat across the Desert Southwest and California
Valleys, Wed-Sat, Jun 24-27.
- Slight risk of heavy precipitation for the Middle Mississippi, Ohio, and
Tennessee Valleys and adjacent areas, Sun-Mon, Jun 21-22.
Detailed
SummaryFor Tuesday June 16 - Saturday June 20:
WPC Days 3-7 U.S.
Hazards For Sunday June 21 - Saturday
June 27: Subtropical mid-level ridging is expected to extend into the
Florida Peninsula and adjacent areas of the Central Gulf and southern Atlantic
coasts through the middle of week-2, increasing the odds for extreme heat in
those areas. Bias-corrected GEFS and ECENS Heat Index guidance for week-2
depicts values peaking near 105 deg F, and the National Blend of Models (NBM)
predicts near-record or record high nighttime minimum temperatures of 76-81 deg
F across much of the Florida Peninsula and a few nearby locations. Some
locations on the Florida Keys may not drop below 85 deg F on one or more
nights. The Probabilistic Extremes Tools (PETs) from the European ensemble
(ECENS), Canadian ensemble (CMCE), and GEFS depict the best chances for high
temperatures above the 85th climatological percentile across the Florida
Peninsula (up to 40 percent on the ECENS PET, and 30 percent on the others).
The slight risk of extreme heat continues through the middle of week-2 when
most tools show the subtropical mid-level ridge flattening across the Southeast
and emerging farther west. Some tools indicate increased chances for extreme
heat later in week-2 as well, particularly raw temperature output and PETs from
the ECENS, but there is too little consensus among the tools to support any
extreme heat hazards then, although the situation will need to be monitored.
During the middle and later parts of week-2, mid-level subtropical ridging
is expected to emerge over the central or interior western CONUS, bringing an
increased risk of extreme heat to the south-central CONUS along with much of
the Desert Southwest and California Valleys. Internal skill-weighted guidance
blending ECENS and GEFS output shows 40 to 60 percent chances for heat indexes
over 105 deg F across most of Louisiana, eastern and northeastern Texas, the
central tier of Oklahoma, and the lower Rio Grande Valley. This appears largely
driven by unusually high humidity, as the PETs depict actual air temperatures
remaining near or below 100 deg F with low chances of reaching the warmest 15
percent of the climatological envelope. Considerably above normal temperatures
cover most of the interior West, including the Rockies, Intermountain West, and
Northwest during the last half of week-2, but temperatures and heat indexes are
expected to remain below hazards thresholds in an absolute sense. The PETs and
internal heat index guidance from the ECENS and GEFS depict low chances for
temperatures or heat indexes to top 100 deg F in these areas.
The building mid-level subtropical ridge also increases the chances for
extreme heat in the Desert Southwest and the California Valleys during the
latter half of week-2. The ECENS and GEFS PETs show 20 to 40 percent chances of
temperatures reaching 110 deg F in the Desert Southwest on some days starting
around the middle of week-2, and similar chances for highs topping out over 100
deg F in the California Valleys. The same tools show 20 to 40 percent chances
for temperatures exceeding the 85th climatological percentile. Internal heat
index guidance also shows increased odds for temperatures or heat indexes of
105 deg F or higher for at least one of the days during the latter half of
week-2.
A frontal boundary (separating the heat in the Southeast from unseasonably
cool air farther north) is expected to be draped from the east-central Great
Plains eastward through most of the Middle Mississippi, Tennessee, and Ohio
Valleys early week-2. This is expected to drive abundant precipitation and
enhanced thunderstorm activity. The PETs indicate at least a 20% chance of
3-day precipitation exceeding the 85th climatological percentile, with the
ECENS PET showing 30 to 40 percent chances across the Tennessee Valley and
northern Arkansas. Uncalibrated ECENS output depicts a 50 to 80 percent chance
for precipitation totals to exceed an inch during the first 2 days of the
period throughout the slight risk area, with a band showing at least a 30
percent chance for amounts topping 2 inches from central Tennessee through
southwestern Mississippi. Toward the middle of week-2, mid-level troughing and
unusually cool surface air is expected to moderate and pull northeastward,
weakening the frontal boundary and bringing an end to the heavy precipitation
threat.
Forecaster: Rich Tinker
$$
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Resources
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts
www.nws.noaa.gov
