Summertime is coming to an end soon, and September is right around the corner. The questions we hear this time of year are often about fall harvest weather for corn and soybeans, planting for winter wheat and our first fall frost.
September Temperature and Precipitation Outlook
For the month of September, NOAA’s Climate Prediction Center released their outlook on August 18, 2022. Across South Dakota, there is an increased likelihood of warmer than average temperatures in the month ahead, with higher chances in the southwest and south central than elsewhere in the state.
Odds are leaning towards a drier than average month of September as well. Statewide, there is about a 40-50% chance of monthly precipitation totaling less than average. This means there is about a 25-30% chance of above average, and the same for near average for the month. South Dakota’s long-term trend has been towards wetter fall seasons, so the month ahead could be drier than what many of us have grown accustomed to.
The combination of warm and dry could be bad news for winter wheat growers that are looking to plant their crop in September. Much of the state’s winter wheat growing area has already been stressed by drought, so timely rains at planting will be critical for establishing good stands this fall in areas that are short on soil moisture.
Fall Seasonal Outlook
For the fall season of September through November, there is less confidence that the warmth forecast for September will continue through the remaining fall months. In northern South Dakota, there are equal chances of warmer, cooler or near average temperatures for the three months overall. Central and southern regions of the state lean slightly warmer for the three-month period.
The fall outlook indicates increased chances of drier than average conditions, also in the central and southern regions that are favored to be warmer than average in the same period. In general, a warmer and drier fall season could be desirable for corn and soybean harvest, as this outlook could lead to good conditions for grain to dry down in the field and avoid propane and grain drying costs at the elevator.
A dry fall season could make for a challenging start next spring, as soils and crops will rely on spring precipitation more than they would with a wetter fall season and moist soils over the winter. Fall is our best season for recharging soil moisture that has been utilized during our growing season. Fall moisture also benefits our pastures and forages in our 2023 growing season.
First Fall Frost
It is too early to tell for certain when the first fall frost will occur. This year, more than most years, there is a lot of interest in knowing when the first frost will occur to knock back the abundant grasshopper population. The first frost is often a “weather” event more than a “climate” event, with just the right ingredients at the right time to dip temperatures below freezing, and often can’t be predicted more than a few days or a week in advance. Climatologically speaking, the first fall frost often occurs in the Black Hills or the northwest region in mid- to late September. Those same regions have seen frost occur as early as the late August/early September, but also as late as early October. In the southeast, the first frost has occurred as late as mid-November, so there is a lot of variability from year to year.