September–October 2021


Head in the Clouds

DNR Climatologist Pete Boulay Helps Minnesotans Prepare for the Weather—and Climate—Ahead

Mary Hoff

 PETE BOULAY loves clouds. From wispy cirrus to threatening thunderheads, Minnesota’s assistant state climatologist has captured their charm in hundreds of photos through his three-decade career. 

But when it comes to the weather they bring, Boulay has his feet on the ground. Using maps and models, charts and calculations, he applies his extensive knowledge of how the movement of our planet through space and time shapes Minnesota’s temperatures and precipitation patterns. The result: information that resource managers, farmers, outdoor recreationists, event planners—in short, pretty much all of us—can use as we confront a changing climate.

Q | What changes in Minnesota’s climate have you seen over the course of your career?

Probably the biggest is that winters are not as cold as they used to be. When I bought a new vehicle, I used to insist on a block heater so I could plug it in for the winter. Now it’s pretty rare to see minus 20 degrees in the heart of the metro area. It can still get cold, but it doesn’t get as cold for as long as it used to. It’s getting wetter, too. 

Q | What do the heat, drought, and fires of the past summer tell us about what to expect ahead? 

Droughts are relatively easy to define when they start, but predicting when they will stop is a completely different matter. Some of the driest years on record, like 1910 and 1976, precede some of the wettest years on record, like 1911 and 1977. A drought could last several years, like the 1987–89 drought, or linger off and on, like the 1920s–30s drought.

Q | The National Centers of Environmental Information recently revised Minnesota’s “climate normals.” How do we determine what’s normal, and why is it important? 

About a century ago, the World Meteorological Organization came out with a way to define climate normal using a 30-year period. Every 10 years, it’s recalculated. Basically, it’s a good guide to compare what’s going on today to a kind of benchmark. It allows us to predict what the weather could be like. It gives you some idea of what you should have in your closet to wear.

Q | What does this mean for Minnesotans who love to fish, hunt, hike, snowmobile, etc.?

If you love recreation, you can still fish, you can still hunt, you can probably hike in anything, but we’ll all have to make some adjustments as habitats and landscapes change. Winter recreation is where we have seen and expect to see more impacts, because of inconsistent ice cover and snow. A lot of the changes we expect are already under way, so be creative and there should be plenty of ways to have fun outside. 

Q | How about for Minnesota’s plants and animals?

If we don’t get extreme cold, it enables invasive species to survive in Minnesota. Emerald ash borer and the Japanese beetle both have a lethal temperature where they die if it’s so cold for so long. If it’s not cold, they can survive the winter. Both are newcomers and cause a lot of damage. 
Q | What do you see looking forward as far as further changes in Minnesota’s climate?

Minnesota is always going to have a wide variety of weather. Some things will change—maybe less ice on the lakes in the winter, maybe less of a snowpack. That’s the kind of change I see.

Q | What should Minnesotans do to prepare for these changes?
People should always be prepared for the weather even if it’s not as cold as it used to be. Arctic outbursts will still happen, and people can still get caught unprepared. I like to quote Alfred Wainwright: “There’s no such thing as bad weather, only unsuitable clothing.” It will be cold enough that you’ve got to be careful. 

Q | How does your work help natural resource managers? 
We provide a lot of products. We post lake ice-out dates on the web every year. We provide input to the U.S. Drought Monitor. We produce precipitation maps. We keep track of the frost depth and other factors that affect flooding in the spring. We’ve been coordinating a large statewide rain gauge network since the 1970s. These volunteers make an outstanding contribution to the base of knowledge required to understand Minnesota’s climate. We create winter snow depth maps. We provide data for the DNR wildlife severity index in the winter.

Q | What makes Minnesota a great place to be a climatologist? 
We’re unique in that we are halfway between the pole and equator and about as far away from an ocean as you can get. Thus we have very well-defined seasons. Not only that, but in the eastern half of the state we typically have more precipitation than evaporation, and in the western half we have more evaporation than precipitation. And then we have 11,842 lakes, with many lakes having their own microclimate. If you’re a weather watcher like me, it doesn’t get any better than that.