As we enter the latter part of the year, July brings to mind barbecues, fireworks, and pool parties. However, this month also surprises us with its unpredictable weather patterns. Swap out the traditional July events with scorching heat, powerful thunderstorms, and an increase in hurricane activity, and you’ll have a meteorologist’s accurate depiction of July.
Here are five common occurrences during this month:
1. Peak of Summer Heat
July marks the peak of summer heat across much of the United States. With the sun at its highest position in the sky following the summer solstice, the land and air warm up gradually. This results in soaring temperatures reaching the 80s and 90s in many parts of the country, while areas closer to the Canadian border or along the coast experience milder 70s. In regions like the Desert Southwest, temperatures can easily spike into the 100s.
2. Rise in Atlantic Hurricane Activity
Although hurricane season is still relatively quiet in July, there is a slight increase in tropical activity. Regions such as the eastern Caribbean Sea, the Gulf of Mexico, and the East Coast become prime locations for potential tropical storm development. On average, July gives rise to around one named storm per year, with hurricanes forming less frequently.
3. Peak of Severe Thunderstorm Threat in the Northeast
While severe weather is commonly associated with spring, July sees its peak in certain areas. With the jet stream shifting northward and weaker disturbances passing through, the hot and humid summer air provides ideal conditions for thunderstorms to form. The Northeast, along with regions extending through the Great Lakes and Plains, becomes a hotspot for severe weather incidents in July. Cities like Boston, New York City, Philadelphia, and Washington, D.C. experience a surge in severe thunderstorm reports during this time.
4. Increase in Southwest Monsoon Activity
In the Desert Southwest, the start of the monsoon season is typically marked by Mother Nature turning on the hose, bringing much-needed rain to the region. A dome of high pressure over the southern Rockies or adjacent Plains draws moisture northward from the Gulf of California and westward from the Gulf of Mexico, leading to daily afternoon and evening thunderstorms over the Southwest’s higher terrain.
During the initial phase of the monsoon in July, thunderstorms may be more windy than rainy, stirring up intense dust storms known as haboobs. As summer progresses, heavy rain and flooding become more common, especially when moisture from a tropical system in the Eastern Pacific reaches the area. This increased humidity can change the perception of the desert climate from dry heat to muggy conditions.
The intensity of the monsoon varies from year to year; for instance, the Southwest experienced its driest monsoon on record in 2020 followed by one of the wettest in 2021. Thunderstorm clusters, known as mesoscale convective systems, are a common sight on radar during July mornings, often covering large areas on satellite imagery. These clusters can bring damaging winds known as derechos if they are fast-moving, or result in flooding if they stall. They are also prolific lightning producers, with thousands of strikes per hour.
Caitlin Kaiser, a digital meteorologist at weather.com, holds both undergraduate and graduate degrees in Earth and Atmospheric Sciences from the Georgia Institute of Technology.
