HydroClim Minnesota for Early April 2021

State Climatology Office - DNR Division of Ecological and Water Resources, St. Paul
Distributed: April 12, 2021


What happened in March 2021:

  • March monthly precipitation totals were generally above normal across the southwest, east central and northeast and below normal in the northwest. The wettest areas were in east central Minnesota where a surplus of one to one-and-a-half inches was common. Most of the precipitation came in the second half of the month with an event on March 23-24 making up the bulk of the precipitation. The Twin Cities International Airport saw 1.55 inches for the two-day period. For the month of March, Stillwater in east Central Minnesota saw 3.53 inches or 1.99 inches above normal. One of the drier locations was in the Fargo/Moorhead area where only .28 inches fell or 1.02 inches short of normal.
    [see: March 2021 Precipitation Total Map  | March 2021 Precipitation Departure Map  | March 2021 Climate Summary Table  |  March 2021 Percent of Normal Precipitation Map]
  • There were two main weather systems that affected the state in March. On March 10-11, a wild springtime storm system brought vivid lightning and some of the earliest large hail on record to parts of southern Minnesota, while blanketing central and northeastern portions of the state with 6-12 inches of snow. The second event was a prolonged soaker that drenched southwest, south central and east central Minnesota.
    [see: Hailstones and Heavy Snow, March 10-11,2021]
  • Other than the heavy wet snow across central and northeastern Minnesota on March 10-11, winter came to an abrupt end. The snowpack eroded rapidly with high temperatures in the 50s and 60s for the first half of the month. Despite the chilly final day of the month, March finished in the top ten warmest for most locations in Minnesota. In the Twin Cities, Duluth and St. Cloud it was the eighth warmest. Rochester had the 9th warmest March and at International Falls March 2021 raked 3rd warmest. Statewide the preliminary average temperature was 7.4 degrees above normal. The coldest temperature found for the month was -21 at Camp Norris in North Central Minnesota on March 1 and the warmest temperature found was 83 degrees on March 29 at Milan in west central Minnesota. [see: Minnesota Climate Trends  |  March climate Summary Table  |  2021 March Departure from Normal Temperature Map]

Where we stand now:

  • The first week of April not only carried the warm pattern from March but amplified it with the warmest temperatures so early in the season. It was 85 degrees on April 5 in the Twin Cities, breaking the old record of 80 set in 1991, and the highest air temperature so early in the season. The final snow depth map of the season was April 1, with the only remaining snow cover in the higher terrain of Cook County. By April 8, even this had disappeared.
    [see: MNDNR April Snow Depth Maps  |  NWS Snow Depth Estimation Map  |  Midwest Regional Climate Center Snow Depth Map]
  • The U. S. Drought Monitor map released on April 8, 2021 depicts 85% of the state with some level of drought designation. Last year at this time the state was free of any drought. About 51% of the state was Abnormally Dry, and 30% of the state in Moderate Drought conditions. A small area in Rock County in southwest Minnesota and along the Red River of the North in northwest Minnesota had Severe Drought conditions. In far northwest Kittson County was a tiny area of Extreme Drought conditions. The U.S. Drought Monitor index is a blend of science and subjectivity where drought categories (Moderate, Severe, etc.) are based on several indicators.
    [see: Drought Conditions Overview]
  • Compared to recent years, the 2021 spring flood season due to snowmelt was on the quiet side. Rivers were on the rise a bit in central and southern Minnesota by April 9 due to the heavy rains.
    [see: Statewide USGS Stream Flow Conditions  |  Central Minnesota Rivers  |  Southeast Minnesota Rivers  |  Northwest Minnesota Rivers, including the Red River
  • Water levels on most Minnesota lakes vary depending on lake and location. Mille Lacs was just above the median level for early April. Minnetonka was at 929.16 feet on April 9, with Grays Bay Dam closed. White Bear Lake was at 924.63 feet on April 12, about a half foot lower than the same time last year. Rainy Lake and Lake of the Woods were in the low end of the median range for early April. Lake Superior was forecasted to be at 601.87 feet on April 9, seven inches higher than the long term monthly average for early April and seven inches below the level in early April 2020. Superior is forecasted to rise over the next month.
    [see: Mille Lacs Lake Water Level  |  Lake Minnetonka Water Level  |  White Bear Lake Water Level  |  Lake of the Woods Control Board Basin Data  |  Corps of Engineers Great Lakes Water Levels]
  • In its first report of the 2021 growing season, the Agricultural Statistics Service reported that topsoil moisture across Minnesota was 12 percent Very Short, 31 percent Short, 53 percent Adequate, and 4 percent Surplus. This is much drier than the same time last year. Pastures were greening up with the warm temperatures.
    [see: Agricultural Statistics Service Crop Progress and Condition]
  • It was an active strong fire season so far, especially with the warm and windy conditions for early April. The cooler and wetter conditions during the weekend of the 9th-11th eased fire danger somewhat. The potential for wildfires is currently rated by DNR Forestry as Low across nearly the entire state. While Moderate in Lake of the Woods and part of Koochiching County persisted. Historically, 80 percent of all wildfires in Minnesota occur during April and May.
    [see: Fire Danger Rating Map]
  • Lake ice out began during the third week of March, about two weeks earlier than the median. As of April 10, lake ice out had progressed into northern Minnesota, still about two weeks to 18 days ahead of the median.
    [see: 2021 Lake Ice-Out Dates  |  DNR Conservation Officer Reports]

Future prospects:

  • The April precipitation outlook indicates a greater than average chances of above-normal values across all but the southern parts of the state, with the highest probabilities in northwest and north central Minnesota. Normal April precipitation ranges 1.5 inches in northwest Minnesota to around three inches in southeast counties. The historical probability of measurable precipitation for any given day in April ranges from 20 percent in the far northwest to 35 percent in the southeast.
    [see: Climate Prediction Center 30-day Outlook  |  April Precipitation Normal Map]
  • The April temperature outlook favors above normal temperatures over the entire state, with a the best chance in the eastern part of the state. Through April 11, the preliminary statewide average temperature was 7.8 degrees above normal. Normal April high temperatures are in the mid to upper 40s early in the month, rising to the low 60s by month's end. Early-April normal low temperatures are near 20 in the north, near 30 in the south. By month's end, low temperatures average in the mid-30s in the north, near 40 in the south.
    [see: Climate Prediction Center 30-day Outlook  | April Temperature Normal Map]
  • The 90-day precipitation outlook for April through June indicates a tilt to above-normal precipitation conditions over northeast Minnesota, otherwise it is equal chances for below, normal and above normal precipitation. The April through June temperature projection favors above normal conditions over not only Minnesota, but most of the contiguous United States.
    [see: Climate Prediction Center 90-day Outlook]

From the author:

After a weekend that was very warm by most measures, Monday April 5th produced some of the highest temperatures ever recorded in early April in Minnesota.

[see: Record Heat, April 5, 2021 ]

Upcoming dates of note:

  • April 15: National Weather Service releases 30/90 day temperature and precipitation outlooks

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Pete Boulay MNDNR Climatologist