September is normally a transition month from summer to fall, with weather conditions ranging from hurricanes to snow.

Below you can read what weather changes you can expect this month.

Cooling down: High and low temperatures take a noticeable dip towards the end of the month. For many, one of the clearest signs that fall has arrived is the cool, crisp mornings that become more common towards the end of September.

Average lows in September will be in the 50s and 60s for much of the Lower 48, while portions of the northern low and higher elevations will experience average lows in the 30s and 40s. Morning lows will remain in the 70s for much of Florida, along parts of the Gulf Coast and the Desert Southwest.

For example, lows in Boston start the month in the mid-60s, but on September 30 the average low is 53 degrees. In Denver, the average low on September 1 is 55 degrees, but drops to 44 degrees by the end of the month.

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But there is still some warmth left: Average highs for the month range between 63 and 70 degrees Fahrenheit (17 and 21 degrees Celsius) across much of the northern region, while temperatures in the southern US will still be around 80 degrees Fahrenheit (27 degrees Celsius), with temperatures between 90 and 104 degrees Fahrenheit (32 and 40 degrees Celsius) in parts of Florida, Texas and the desert southwest.

For example, the average high temperature in early September in Atlanta is 87 degrees, but by the end of the month it is in the low 80s. In Minneapolis, the average high temperature is in the low 70s at the beginning of the month, but drops to the mid 60s by early October.

Shrinking daylight: The hours of sunlight decrease in September with the autumnal equinox on September 22nd this year. The autumnal equinox is when the sun shines directly on the equator, meaning that both the Northern and Southern Hemispheres receive the same amount of daylight. The amount of daylight is not exactly 12 hours on the equinox in the United States, but it is close in many locations.

Areas farther north see a greater change in daylight hours in September. Locations in the northern tier lose more than an hour of daylight from the beginning to the end of the month. Anchorage, Alaska, receives nearly 2 hours and 45 minutes less daylight on September 30 compared to September 1.

Sunrises occur later during the month, but the earlier sunsets are more visible and, for many, a sign that winter is coming.

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In September, four named storms form in the Atlantic Ocean. Two to three of them become hurricanes, and one of them reaches major hurricane status (Category 3 or higher on the Saffir-Simpson scale for hurricane-force winds).

The last few Septembers have been busy. Six named storms formed last September. Two major hurricanes – Fiona, then Ian – occurred in September 2022. In September 2020, there were 10 named storms with four hurricanes.

Snow… really: It may sound too early, but there are areas where snow can already fall in September.

It is most common in the higher elevations and in Alaska, where Fairbanks averages 2.4 inches of snow in September. Cheyenne, Wyoming, averages just under an inch of snow, although measurable snow does not fall every September.

Parts of the Plains, Great Lakes and northern New England also received snow in September. Mount Washington, New Hampshire, averages 1.2 inches of snowfall in September.

In early September 2020, one of the first Front Range snowstorms ever produced snow from Montana to New Mexico.

Last September, a historic September snowstorm broke records in the Northern Rockies, dropping as much as four feet of snow.

Monsoon to Santa Ana: One change in the western pattern is the return of Santa Ana winds. Strong high pressure over the inner west results in an offshore pattern with winds flowing from the higher elevations of the desert regions through canyons and passes in Southern California. Wind speeds increase as they are funneled through the mountain passes. High temperatures often accompany Santa Ana winds.

The combination of low humidity and strong winds can increase fire danger, especially in early fall as California’s dry season ends.

Meanwhile, the southwest monsoon season is coming to an end in late September, also due to a shift in wind and temperature patterns in the region.

In the summer, the wind blows from the ocean to the southwest, resulting in wet weather in the region. In the fall, this changes as the wind blows from the land to the ocean, as the land begins to cool and the water warms.

Linda Lam is Chief Meteorologist at weather.com and began her career in 2006 at The Weather Company (formerly WSI).