COLUMBUS, Ohio (WCMH) -- We have made it into the fall months here in central Ohio, and boy did it feel like it this past weekend. Quite a first full weekend of September, with well below normal temperatures. Yes, the Autumn Equinox isn't until Sunday, Sept. 22 around 8:44 in the morning, but the fall months of September, October and November are upon us!
Simply put, it will likely be a continuation of what we saw during the summer months, but with less extreme rainfall deficits. However, it should be noted, the summer rainfall deficit was 7.67 inches (Jun-Aug)., and during the fall months of Sept.-Nov., we only average 8.83 inches of rain. That would be like us only picking up 1.16 inches over the three-month period.
Below is a table of the normal rainfall and temps for the months:
| Month | Rainfall | Avg. High | Avg. Low |
| Sept | 3.14" | 77.8° | 56.5° |
| Oct | 2.90" | 65.5° | 44.8° |
| Nov | 2.79" | 52.3° | 35.0° |
The past summer ran between 1.5°-2.3° above normal on average each month, and roughly 2-3 inches below normal each month. This would make it a more warm and dry period. While it does appear we will start to break that very dry pattern a bit heading through the fall, we are not likely to see a very wet pattern either.
One thing working in our favor, is that according to the Climate Prediction Center at NOAA, we have a 74% chance of a La Niña pattern during the December-February period. As we transition to it, we should start to see a shift away from the blocking pattern we have been stuck in for a good portion of the summer. Below is a map of the typical La Nina pattern in the winter months.
I still anticipate above normal temperatures to continue through the fall months (on average), we should start to see a wetter pattern starting to emerge as we progress toward winter. In the short term (for the next few months), this will look more or less like a more seasonal precipitation type forecast.
Going back to the temperatures, we have been above normal now every month since August 2023, when we were 1.0° below normal. While the first eight days of September will go down as being slightly below normal temperature-wise, we will see a shift for the second full week of the month to back above normal.
One interesting thing of note from the first week of the month, we did have some warm, above normal, afternoons, but because of the incredible drought much of the state is in, our very dry air gave us some very cool mornings, which offset the abnormally warm afternoons. This pattern should gradually moderate as we head through the month of September.
As far as the latest outlooks, for the fall, you can see the three-month outlook from the Climate Prediction Center at NOAA with better chances for above normal temps.
As far as precipitation goes, the forecast is a bit more murky, as the Climate Prediction Center has equal chances for above or below normal.
Looking at the forecast model data for the next week to week and a half, it looks like we are going to continue with a generally dry pattern. In fact, even the 3-4 week outlooks, which would take us into early October, have us with better chances for drier than normal weather to continue. Thinking ahead to the wetter than normal pattern expected for the winter months during a La Nina patter, this would favor more seasonal conditions into October, and possibly a shift to a slightly wetter than normal pattern into November.
One thing to note, temperature averages are a bit less sensitive to an outlier. On a day in early September to skew the data by 1° for the entire month, we would have to have a high of 110° and a low of 90° (roughly). However, we could get one record rainfall, and it could not rain the rest of the month, and we could have what would be considered a "normal" month for rainfall.
As we progress through the fall, the amount of times we have record rainfall of 2 inches or more goes down. In fact, historically, we have had seven Septembers with a daily 2 inches or more rainfall, six Octobers, and only twice in November have we had a daily rainfall of 2 inches or more.
