While the monsoon is arriving later than usual this year, meteorologists promise that it’s on its way.
The North American monsoon is a seasonal wind shift from a dry, westerly flow to a moist, southerly flow that officially runs from June 15 through Sept. 30, although monsoon moisture doesn’t usually reach northern Arizona until early July.
“The monsoon season is delayed and occurring later than normal this year,” said Megan Taylor, lead meteorologist at the National Weather Service in Flagstaff. “We had an unusually cool spring that led to the delayed start. The monsoon circulation relies on warm high pressure building over the region, which did not happen until later in the summer this year.”
While some areas in Northern Arizona experienced rain last week, Taylor stated that this week will see more chances for rain.
“The heat we’ve experienced is unusual for this late in the season,” Taylor said. “We typically experience our greatest heat impacts in late June or early July, but the delayed start to the season has prolonged our heat into July.”
Arizona had a very wet 2022 monsoon season, with most of the state seeing rainfall levels well above normal. National Weather Service data shows that the 2022 season tied for the seventh-wettest July-September period on record.
Above-average winter precipitation earlier this year significantly reduced drought levels across the state. Current predictions are for below-normal precipitation and above-normal temperatures for most of the state.
Monsoons occur when intense heating in the southwestern United States in the early summer months creates wind shifts that carry moisture inland from the Gulf of California and eastern Pacific Ocean. Northern Arizona typically sees its hottest and driest weather during June due to a strong subtropical ridge of high pressure in the atmosphere over Mexico. This ridge of high pressure then shifts northward, bringing moisture with it. This combination of moisture levels triggers the beginning of the monsoon season.
The rainfall brought by monsoon storms accounts for between 40% and 50% of the annual precipitation in northern Arizona. It refills reservoirs and water supplies and is important to farmers and ranchers who depend on this water. The arrival of the monsoon also reduces the threat of fires.
There are many safety tips that the overcautious can keep in mind during the monsoon. Lightning can strike miles away from a thunderstorm, so if outside, seek shelter in a vehicle and not under tall objects, like trees.
Winds can exceed 100 mph and dust storms can strike suddenly. Stay inside to avoid dust inhalation and be aware of low visibility driving conditions. If caught in your vehicle during a dust storm, pull over, put the car in park, turn off the lights and take your foot off the brake.
Flash flooding is another threat. Just six inches of water can sweep an adult off their feet and two feet of water can wash away a car. Never drive through a flooded roadway.
Additionally, when rain falls on land previously burnt by wildfires, it can collect debris and create a moving mass of mud, sand, soil, rock and water.
