Cool and Wet Spring 2018 Back »

Courtesy: Maurice Pullin [CC BY 2.0] via Wikimedia Commons

As we traverse our way through this never-ending winter season, warmer weather is on our minds. Spring is slow to come this year, as late season snowstorms continue to impact South Dakota.

Current Conditions

Indeed, as of April 10, it is the coldest start to April on record for many locations in the state. For the first third of the month, air temperatures were 12 to 20 degrees below average nearly everywhere statewide.

Soil Temperatures
Soil temperatures are struggling this season. Most of Central and Southern areas are thawed out through the profile, but Northern and Eastern areas still have some frost in the soil profile. As of April 10, frost depth was still two to four feet deep in the Northeast, according to the SD Mesonet (

When considering planting conditions, ideal soil temperatures for corn are above 50 degrees F. Currently, the SD Mesonet is measuring 30 to 48 degrees F at four inch depth. This is about 12 degrees cooler than last year at this time for most locations. As we are entering into the early season for corn planting per the crop insurance rules, we have a little way to go before the soils are ready for corn seeds. For spring wheat germination, ideal soil temperature is around 40 degrees F, so even that crop is slow to get planted this year in many areas.

South Dakota Soil temperature map. Contact Laura Edwards at 605.626.2870 for more information.
Figure 1. Soil temperature at four inch depth as of April 11, 2018.
Source: SD Mesonet

Last Frost
A lot of gardeners are asking when the last frost will occur. It is still too hard to say for sure, as the outlook for the next two weeks (through April 24) continues to show a cool and wet pattern across the state. The active storm track will likely continue during this time. Average last frost ranges from late April to mid-May, moving from east to west across the state.

South Dakota median last frost date map. Contact Laura Edwards at 605.626.2870 for more information.
Figure 2. Median date for spring season’s last 32 degree air temperature. Source: SD Mesonet

April Outlook

April will be a slow slog through this cool and wet pattern. It has proven to be the most challenging for calving and lambing in years. Hundreds of mule deer have suffered in the Northwest as well. The moisture will be beneficial in the long run for improving drought conditions in pastures and grazing areas, and providing early season soil moisture in cropping areas. Spring-like weather will come, as it always does, and we will embrace the warm weather.

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