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Climate Observations: Seven of the warmest March months in state history occurred over the past 20 years.

Mark Seeley

January 31, 2020

2 Min Read
green grass sprouting through snow
MODERATE MARCH: Temperature trends in Minnesota in March are getting warmer — about 5 degrees F warmer than a century ago. Nataba/Getty Images

In recent years, I have written much about climate trends, especially those that we have measured on the month of March. These trends are significant, and they are all interrelated.

Seven of the warmest months of March in state history have occurred over the past 20 years, including the all-time warmest back in 2012 when the average daily temperature across the state was 14 degrees F greater than normal.

On a statewide basis, the average daily maximum temperature in March today is about 3 degrees warmer than it was 100 years ago. Over the last decade, maximum daily temperatures in March have exceeded 70 degrees and 80 degrees in several counties, and in 2012 alone nearly 900 daily maximum temperature records were tied or broken within the Minnesota climate observing network.

On a statewide basis, the average March daily minimum temperature today is about 5 degrees warmer than 100 years ago.

Over the last five years, 382 daily warm minimum temperature records have been set in the climate observing network. Looking further back over the past decade, more than 1,000 such records have been set. Many of these records are associated with a preceding mild winter, as well as an absence of snow cover in March, so the landscape can more readily heat up with the increasing daylength and overhead sun angle during the month.

Yet another climate element that has affected these temperature patterns is cloud cover. In years when a large number of overnight warm minimum temperature records have been set, there has been a good deal of nocturnal cloud cover that has prevented overnight temperatures from dropping below freezing.

In this situation, the soil continues to thaw out even during the overnight hours, and loss of soil frost occurs early on the calendar. Conversely, in years with less-than-normal cloud cover (2012), the daily maximum temperature can amplify to record high levels bringing 60, 70 and even 80-degree temperatures to many parts of the state.

The prevalent cloud type during the month has a great deal of influence on the temperature pattern.

Dominance of low-level stratus clouds will more readily keep overnight minimum temperatures higher than normal by limiting the long-wave radiation loss from the ground at night.

Dominance of scattered cumulus clouds — more vertical in nature — will amplify the daytime incoming short-wave radiation and help push daytime maximum temperatures to higher-than-normal levels.

For a cursory assessment of what to expect in March 2020, visit the NOAA Climate Prediction Center. See if above or below normal temperatures are expected and consider the presence or absence of snow in your area. Both can be good indicators of how soon the soil will lose its frost.

Seeley is professor emeritus of climatology at the University of Minnesota.

About the Author(s)

Mark Seeley

Mark Seeley is an Extension professor emeritus of meteorology and climatology at the University of Minnesota.

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