The transition to autumn is defined by three different perspectives: celestial mechanics, calendar convention, and local climate experience. Each definition offers a distinct starting point, reflecting different ways humans track the changing seasons. The date that marks the official beginning of fall depends entirely on whether you consult an astronomer, a meteorologist, or simply step outside to feel the air and observe the trees. For Maryland residents, the practical, climatic shift is often the most meaningful, though the other definitions provide a consistent framework.
The Astronomical Beginning (The Equinox)
The start of fall is determined by the Earth’s orbit around the sun, specifically the autumnal equinox. This event marks the exact moment when the sun crosses the celestial equator, moving from the Northern Hemisphere to the Southern Hemisphere. For the Northern Hemisphere, this crossing typically takes place on either September 22nd or September 23rd. The equinox signifies a day when daylight and nighttime hours are nearly balanced globally. Following the equinox, the Northern Hemisphere begins to tilt further away from the sun, causing the days to grow progressively shorter until the winter solstice.
The Meteorological Definition (Fixed Calendar Dates)
Meteorologists and climatologists use a fixed calendar system for the seasons to maintain consistency for data tracking and forecasting. This approach divides the year into four three-month periods based on the annual temperature cycle. Under this standardized system, meteorological fall is always September 1st, regardless of the equinox or local weather conditions. The season runs for three months, encompassing September, October, and November. This fixed schedule is practical for scientists analyzing large datasets, as it eliminates annual variations caused by the Earth’s elliptical orbit and leap years.
When Fall Feels Like Fall in Maryland (Climatic Shift and Foliage)
Climatic Shift
The subjective experience of fall in Maryland generally occurs several weeks after the meteorological start date. Average high temperatures in September typically hover around 77°F, feeling like a late summer extension. The noticeable shift to cooler conditions, with average daytime highs consistently dropping below 70°F, usually takes place around the beginning of October in the central and eastern parts of the state. The first frost, a significant marker of the end of the growing season, varies considerably across Maryland’s diverse geography. Higher elevations in Western Maryland, such as Garrett County, often see their first frost in late September, while coastal areas may not experience it until early or mid-November.
Foliage Progression
The most anticipated visual marker of autumn is the foliage, which follows a predictable progression across the state based on elevation and latitude. The color change begins earliest in the Appalachian mountains of Western Maryland, where cooler temperatures accelerate the process. Peak color in Garrett County typically occurs around mid-October. As the season progresses, the peak color moves eastward and southward toward the lower elevations. Central Maryland, including the Baltimore area, generally reaches its peak viewing time around the beginning of November, with the Eastern Shore peaking in early to mid-November due to the tempering influence of nearby bodies of water.