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Agronomic Crops Network

Ohio State University Extension


Harvest Season Climate Outlook

The summer growing season has played out just like a typical El Niño year would. Temperatures averaged about one degree below normal across the state for summer with rainfall below normal in the western parts of Ohio and slightly above normal in the eastern parts of Ohio. For rainfall it was some extremes that made up that average though with a really dry May and June followed by a wet July and early August then a dry late August and early September overall. Those rainfall swings spell weed central.

There are a few changes to the harvest climate outlook from what we published back in late May. El Niño is the driving factor. It is creating wind shear in the atmosphere keeping most of the tropical activity off the U.S. East Coast. This is likely to persist overall into October meaning rainfall in the Ohio Valley will be limited by tropical activity. 

The autumn El Niño events most like this year includes 2015, 1997, 1987, 1982, 1972, 1965, 1963, and 1957. The attached images show the summary of historical El Niño events like the 2023 one for the period of September through November for both temperatures and rainfall courtesy of NOAA's Physical Science Laboratory. Temperatures are not far from normal and precipitation is slightly drier (with drier first 2/3rds and wetter last 1/3rd).

El Niño Temperatures   El Niño Rainfall

September is forecast to be slightly warmer (but with swings in those temperatures from warm to cool to warm) along with rainfall at or below normal. Even though temperatures are forecast to be slightly warmer than normal, we do not see a really hot late September which has been a theme in recent years.

October looks to swing into a cooler than normal month with rainfall again near or below normal. Unlike many of the recent early Octobers which have been hot, this October may be cooler with some lows down into the 30s or lower 40s. Current projections indicate the first freeze to likely be within a week or so from normal so not a lot of deviation from normal.

As harvest season kicks in, the one concern to monitor is a switch to a warm and wetter November. Historical El Niño events and the climate models have been suggesting a wetter November for some time. Harvesting earlier than later may be in the cards this autumn.

Finally, the winter season will continue to feature El Niño meaning a slightly warmer winter with precipitation near or slightly below normal.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.