Long Range Weather Forecast Discussion September 24-October 8
1630 PM EDT Mon. Sep. 21, 2026Sep. 24-28: Guidance agrees on the flow with a trough in the Northwest and an upper low in the East by the Weekend. A zonal flow with above-normal heights is in between.
An upper low over the Mid-Atlantic and Northeast late in the week and into the weekend will support a coastal surface low. This system will bring strong, gusty onshore winds that may lead to coastal flooding and beach erosion. An upper ridge persisting in the south-central states will support warm temperatures. Pacific moisture will flow around the ridge to produce additional rainfall across the Southwest late in the week, though in smaller amounts than the very wet pattern likely Tuesday-Wednesday. This moisture should spread into the Plains as well, with rain chances that also reach the Mississippi Valley over the weekend. A cool pattern is forecast in the Northwest due to a trough and precipitation.
Sep. 29-Oct. 3: Guidance remains in good agreement during this period. A trough is forecast in the Northwest with a nearly zonal flow and above-normal heights across the remainder of the country.
A front moves out of the Mississippi Valley to the Midwest on Thursday, bringing rain and storms to the region. The system moves into the East on Friday as it weakens, with rain mainly for the Northeast. Scattered showers and storms are forecast for portions of the Gulf Coast and the Southeast.
TEMPERATURES
Yellow-2-4°F Above
Orange-4-6°F Above
Red-6-8°F
or Greater Above
Light Blue 2-4F Below
Medium Blue-4-6F Below
Dark Blue-6-8F or Great Below
Above-normal temperatures are forecast from the West Coast to the Midwest and the Gulf Coast. Anomalies could exceed 6°F in some northern Rockies and South-Central states.
PRECIPITATION
Yellow 35%Below
Brown-35-45% Below
Dark Brown-45-55% Below
Light Green-30-35% Above
Medium Green-35-45% Above
Dark Green-45-55%Above
Above-normal precipitation is forecast for portions of the northern and central Rockies and the Plains. The probability of occurrence is 35-40 percent. Below-normal precipitation is forecast for most of the Mississippi Valley, the Midwest, and the Great Lakes region to the Gulf Coast. The probability of occurrence is 35-40 percent.
Oct. 4-8: The GFS has a ridge along the West Coast and a trough in the Rockies, with another ridge further east. The ECMWF has a ridge in the West and a trough over the Northeast.
Rain and snow will be possible in the Four Corners Sunday and into Tuesday. This is due to moisture flowing north of the western side of a ridge. Scattered showers and storms are possible for the Gulf Coast.
TEMPERATURES
Yellow-2-4°F Above
Orange-4-6°F Above
Red-6-8°F
or Greater Above
Light Blue 2-4F Below
Medium Blue-4-6F Below
Dark Blue-6-8F or Great Below
Below-normal temperatures are forecast for most of the Northwest and western Montana. Anomalies are expected to be near 4°F. Above-normal temperatures are forecast for the Front Range of the Rockies, eastward to the Southeast, Midwest, and the Great Lakes region. Anomalies could be near or greater than 6°F across portions of the Southwest and the southern Plains.
PRECIPITATION
Yellow 35%Below
Brown-35-45% Below
Dark Brown-45-55% Below
Light Green-30-35% Above
Medium Green-35-45% Above
Dark Green-45-55%Above