The Old Farmer’s Almanac September forecast calls for broad regional differences across the United States, with several areas expected to run cooler and wetter than historical averages. The publication says the outlook is a month-ahead guide, not a day-by-day map, and it uses solar science, climatology and meteorology to compare expected conditions with historical patterns.
One region is forecast to average 59 degrees in September, 2 degrees below average, with 5.5 inches of precipitation, about 2 inches above average. The Almanac divides the country into zones, so readers should read each regional outlook as a broad tendency rather than a precise local forecast.
The Old Farmer's Almanac zones
In that same region, the month opens with showery, cool conditions through September 7, turns sunny but still cool from September 8 to 11, then shifts back to rainy periods before sunshine returns from September 12 to 19. Showers and cool conditions are forecast for the rest of the month.
The Atlantic Corridor is expected to see scattered thunderstorms from September 1 to 12, with warm conditions giving way to cooler weather. From September 13 to 23, the north is forecast for scattered showers while the south stays sunny, and the final week brings isolated showers and cool conditions. Its September temperature is forecast at 68 degrees, 1 degree below normal, with 3 inches of precipitation, about 1 inch below average.
Appalachians and Southeast
The Appalachians are expected to start September sunny and warm before scattered showers bring cooler conditions from September 7 to 12. From September 13 to 23, the north is forecast for isolated showers while the south remains sunny, followed by showers and cool weather from September 24 to 27. The month is expected to end with showers in the north, sunshine in the south and milder conditions, with an average temperature of 63 degrees and precipitation around 2 inches below average.
The Southeast outlook calls for sunny and mild conditions to open September, then thunderstorms before sunshine returns from September 8 to 18, alongside cooler weather. Another sunny and mild stretch follows through September 24, and the region is expected to end the month sunny as cool conditions turn warmer. The forecast puts the Southeast at 74 degrees, 1 degree below average, with 2 inches of precipitation, about 3 inches below average.
Florida in September
Florida begins September with scattered thunderstorms and turns from warm to cooler through September 11. From September 12 to 20, the north is expected to be sunny while the south sees thunderstorms, with mild temperatures across the region. Sunshine is forecast to continue in the north through the end of September, while isolated thunderstorms remain possible in the south.
The Almanac’s method blends solar patterns, historical weather conditions and current solar activity with climate data and large-scale signals such as El Niño and La Niña. For readers planning travel, outdoor work or seasonal events, the practical takeaway is to watch the regional pattern first: cooler and wetter in some areas, drier in others, with local conditions varying by part of each zone.
