After a first half of September which was 5-10 degrees below average, the second half of September will average 5-10 degrees above average making September in the end a near average month but marked by significant differences in the month. Temperatures the week of September 19-25 will run 10-15 degrees above average with no risk of frost.
Rainfall will remain limited in most areas for the rest of September as well. Some rainfall will occur Tuesday September 19 through Wednesday September 20. Rainfall will average less than a tenth of an inch in the southeast half of the state to 0.10 to 0.50 inches in the northwest half with isolated higher totals. After September 20, the next chance for rain does not come up until around Sept. 26 or 27.
Temperatures are likely to relax closer to normal in October after the warm late September. Rainfall is also expected to increase some especially in the second half of October. We expected October rainfall to be near or slightly below average which is close to 2 inches for the month on average.
Tropical activity looks to stay east of Ohio in the coming weeks. In fact, with storms well east it is enhancing high pressure and drier conditions over the region locally. Historically, storms tend to shift into the Caribbean and Gulf of Mexico once we get to October and November. We will have to wait and see if some of that moisture would make its way back into our region.
There is really no risk of frost and freeze conditions for the rest of September. At times we do see historically late September frosts in Ohio but none are expected this year.
We have been talking in recent months that data suggest a normal to later than normal frost/freeze in Ohio and that looks still to be the case. Sometime in October we will likely see our first widespread frost and possible freeze and typically that arrives the first 2-3 weeks of October but chances are growing it will be in the middle to end of the month of October.
La Nina Watch issued by NOAA Climate Prediction Center
Confidence is still low to moderate but the NOAA Climate Prediction Center has issued a La Nina watch for cooler equatorial Pacific Ocean water this winter.
This could lead to a winter and early next spring that is wetter than normal with temperatures starting winter warmer than normal and turning normal to colder than normal. It is too early to tell, but those are some of the early indications.
Two week rainfall outlook
The outlook for the next two weeks is normal to below normal rainfall for early harvest in the eastern corn, soybean and wheat areas with much above normal rainfall in western areas as the NOAA/NWS/OHRFC graphic shows.