What To Expect In The Weather In August | Weather.com (2024)

Weather changes typically begin to emerge in August as we move through the final month of summer. This includes an increase in hurricane activity and decreases in daylight and temperatures.

Here's a closer look at what to expect in August:

Atlantic hurricane season ramps up. The Atlantic hurricane season officially runs from June through November. In most years, the first two months of the season are usually benign. Then comes August, and it's almost as if a switch is flipped.

The third named storm typically forms by Aug. 3, with the first hurricane developing by Aug. 11. This year, there have been five storms and one hurricane through the end of July.

August sees more than three times the number of named storms as July, on average, and about double the number of June and July storms combined. Several factors contribute to the seasonal ramp-up:

-African easterly waves, or tropical waves, are most developed and often serve as a seed for tropical development.

-Saharan air layers (surges of dry air into the central and eastern Atlantic Basin, which normally squelch tropical development in those areas) tend to give way in August as the parade of African easterly waves gradually adds moisture. This effectively opens up more favorable real estate for tropical cyclone development.

-Wind shear (the change in wind speed and/or direction with height, which can rip apart a tropical cyclone wannabe) tends to be lower.

-Sea-surface temperatures rise toward a peak in early fall.

-Instability, or the atmosphere's ability to generate convection (thunderstorms) to help initiate tropical cyclones, also rises toward an early-fall peak.

Keep in mind that averages and climatology are no guarantee of an outcome in any individual hurricane season.

Tornado risk is highest in parts of the northern tier. Tornadoes are a risk in August, particularly in the northern tier of the country, even though the average number of twisters decreases from July.

The higher risk extends from the Northern Plains to the Midwest and in parts of the Northeast and mid-Atlantic because the jet stream is located farther north toward the Canadian border.

Tropical cyclones can also produce tornadoes.

August is the wettest month in parts of the South and Alaska. The Southwest monsoon is usually in high gear in August and sometimes results in severe thunderstorms.

August is the wettest month on average for most of Arizona, New Mexico and southern Colorado because of monsoonal moisture.

Portions of the Southeast and Gulf coasts also experience their wettest month in August. Afternoon and evening thunderstorms are common there, and rainfall from tropical cyclones sometimes occurs.

Average temperatures begin their decline. Much of the country experiences the warmest time of year in July.

However, August is typically the warmest month for much of the Southern Plains, lower Mississippi Valley and parts of the northern tier from North Dakota to Washington state.

The rest of the U.S. begins to cool off. This translates to afternoon temperatures in the 80s and 90s for most.

Portions of the Desert Southwest remain the hot spot, with average highs above the century mark.

Meanwhile, areas from the upper Mississippi Valley into northern New England often cool into the 70s as more potent cold fronts begin to pass through the northern U.S. again, particularly later in the month.

Overnight temperatures also begin to drop. Slightly lower humidity allows for cooler lows in the 50s and 60s for much of the East, while the Gulf Coast remains in the 70s with humidity still hanging on.

Low temperatures remain in the 70s and even the 80s in the Desert Southwest as monsoonal moisture continues flowing into the region.

The coolest air is typically found in parts of the higher elevations of the West, where lows drop into the 30s and 40s.

The length of daylight also quickly declines through August as the autumnal equinox – 12 hours of day and night – approaches in September. Most cities in the northern half of the nation lose two to three minutes of daylight each day in August.

The sunset in New York City is at 8:11 p.m. on Aug. 1, but by Aug. 31, the sun dips below the horizon at 7:30 p.m. In Seattle, the sun sets at 8:43 p.m. on Aug. 1 but sets 52 minutes earlier at 7:51 p.m. on Aug. 31.

Snow can start to fall in the Rockies. Snow becomes a fairly typical occurrence in late August in the highest peaks of the Rockies, especially the Canadian Rockies.

America's northernmost town – Utqiaġvik, Alaska, formerly known as Barrow – typically sees its first measurable snow, at least 0.1 inches, on Aug. 25, based on the latest 30-year average from 1991 to 2020. Fairbanks typically experiences its first measurable snow in late September but has recorded snow as early as Aug. 25 in 1995.

Early-August snow is more unusual but did occur atop Pikes Peak and Mount Massive in the Colorado Rockies in 2017. Snow was also spotted in Aug. 2019 in Colorado. Last year, Pikes Peak observed snow in mid-August.

Snow is not always confined to the highest elevations in August. Great Falls, Montana, saw its earliest snow on Aug. 22, 1992, the same year its only below-freezing temperatures were recorded in August.

In the East, Mount Washington, New Hampshire, has recorded snow in August, with an average of 0.1 inches falling during the month. The most snow measured there in August was 2.5 inches in 1965.

Linda Lam is a senior meteorologist at weather.com. Growing up in Massachusetts she developed a fascination for winter storms and hurricanes that led her to pursue a career in meteorology.

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