DES MOINES, Iowa — “It would actually be nice outside if it weren’t for this wind!” How many times have you said, heard, or thought of that exact statement? If it’s March or April, then probably quite a bit.
As soon as we leave the single-digit temperatures behind and the snow melts away, the wind seems to kick it up a notch and put a damper on the spring months. It’s true, the wind is stronger in the spring!
In Des Moines, March and April both average wind speeds over 12 mph. In March 2022, Des Moines had an average wind speed of 11.8 mph, but there were still 8 days in which the average wind speed was over 15 mph.
Why is there wind?
The earth is not evenly heated due to its curvature and its 23.5° tilt. This naturally results in warmer air at the equator and colder air at the poles. Temperature gradients at the surface and above result in rising and sinking air, which is how we get low pressure and high pressure.
High pressure air constantly moves toward low pressure air in an attempt to even the pressure out, however that cannot happen. As high pressure moves toward low pressure the wind in between changes accordingly. Less space between high pressure and low pressure creates a tight pressure gradient which results in stronger wind.
The season of transitions
Spring is quite literally a season of transitions. As we transition from the three coldest months of the year (December, January, and February) to the three warmest months of the year (June, July, and August), the polar jet stream retreats north to the Arctic where it will remain until fall.
During the spring months, the jet stream has a large influence on the weather we experience here in Iowa. Warmer air masses surge north and meet up with colder air that has been in place over the course of the winter. This creates tighter temperature gradients. As discussed above, tighter temperature gradients mean more rising and sinking air which then creates tighter pressure gradients resulting in stronger wind speeds.
The summer is when the jet stream will have less of an influence on weather in Iowa. In the summer the difference in temperature between the north pole and mid-latitudes (where the U.S. is) is a lot smaller since the north pole sees a lot more sunlight and thus, warmth. Weaker pressure gradients inevitably result in weaker wind speeds. During each month of the summer, Des Moines experiences an average wind speed below 10 mph.