Be Ready: Des Moines Weather Swings from Super to Severe

Rain can occur more than 300 days a year in Des Moines, but it's usually wettest from early April to late September. Aside from creating a delightfully green environment, the weather can feel delightful between 70 and 80 degrees F after the cold of winter ends and before the heat and humidity of summer kick in.

By mid-autumn, the weather is pleasant again before diving down below 20 degrees F in winter -- what is known as our "drier season."

Tornado Season

Tornado season generally begins in March and may last through early August. Thunderstorms are a prerequisite of tornadoes, which can include hail the size of golf balls. Also, if you're a newcomer, keep in mind the word "generally."

Tornadoes can even occur here during the cold season despite mostly being warm weather phenomena. If you were here in November 2015, you may remember the tornado that crossed over Des Moines International Airport.  Snow followed six hours later.

A local myth in Des Moines says that tornadoes don't cross bodies of water and, consequently, don't land here. But being located between two rivers doesn't prevent us from being vulnerable to twisters even if they seldom touch down.

As of early March 2017, 19 tornadoes had already occurred in Iowa ranging from EF-0 to EF-2 on the Fujita-Pearson tornado scale. The top of the scale is an EF-5 (also called F-5) whirling at well over 200 miles per hour. None traveled through Des Moines.

Tornado Alley & Its Causes

So, weather can be a wild ride here although it is a rarity for powerful tornadoes to touch down in or near the city. Part of living in Des Moines is acknowledging that you live in Tornado Alley, which reaches from southern Minnesota down to Texas. Everyone in this vast region needs to practice tornado preparedness.

Although the American Midwest is famous for tornadoes, they occur throughout the world, including the United Kingdom. We're in the middle of a huge freeway of air masses merging from the Arctic (cold and wet), the Rocky Mountain West (warm, dry and dusty) and the Gulf of Mexico (warm and wet). Together, they rise, swirl and cause damage.

Severe Weather Preparation

One crucial action in preparing for a weather disaster is to keep a "go bag" on hand containing a change of clothing, water and snacks.

Another step is to select an area in the lowest level of your home and away from windows, skylights and large ceilings. If possible, avoid sheltering directly under a floor from which heavy objects may cave in. Then practice going to your safe spot, but always grab your go-bag and radio first. If possible during a real event, grab a mattress to cover yourself and others for extra protection.

An emergency preparedness report by the City of West Des Moines covers how to protect yourself and your family from lightning, floods and other severe weather events in addition to tornadoes. The report reminds readers that a severe thunderstorm "watch" is an announcement from 2 to 6 hours before dangerous weather may develop in your area. In contrast, a "warning" occurs when severe weather is imminent and requires you to move to safety.

Des Moines has 28 sirens throughout the city for storm warnings. If you're indoors, it may be difficult to hear the sirens. So, you need to listen for warnings on a battery-powered radio.

Preparing for Safety in an Apartment

No matter where you live or work, you need a safety plan. If your apartment community has a severe weather safe room, practice going there for shelter. Bathrooms and hallways in ground floor apartments are good choices.

If there is no community safe room and you live on an upper floor, go to your building's lowest point, such as an underground garage or beneath a first-floor stairwell. Before bad weather arrives, you can also arrange to shelter with a first-floor neighbor. It's better to worry about safety than about being intrusive.