According to the National Centers for Environmental Information (NCEI), the statewide average October precipitation was 4.41 inches, 1.37 inches above the long-term mean (1991-2020). This was 0.22 inches greater than October 2020 and 0.76 inches greater than September 2021. October 2021 ranks as the 14th wettest on record (Table 1).
October was a wet month in Ohio this year. The eastern half of the state received 3 to 4 inches, while the western half accumulated as much as 7 inches (Fig. 1). For the northwestern portion of the state, this was more that 200% above the long-term mean (1991-2020), with near or slightly below average pockets in eastern and southwest Ohio (Fig. 2).
Defiance County in northwestern Ohio received the greatest amount of precipitation in in October, measuring 7.58 inches, making this the wettest October on record for that county in the 127-year period (Fig. 3). It was also the wettest October on record for several other counties including Williams, Fulton, Lucas, Henry, and Wood. The driest county during October was Monroe County in eastern Ohio, with 2.63 inches of precipitation, making it the 63rd driest October for that county. Historical statewide trends show that during 1895-2021, the lowest recorded precipitation was 0.23 inches in 1963, with the greatest occurring in 1919 at 6.42 inches (Fig. 4).
October 2021 was the warmest October on record (1895-2021) for the state of Ohio. The average temperature was 60.6°F which was 6.9°F warmer than the long-term mean (1991-2020). This was also 7.1°F warmer than October 2020 but 6.4°F cooler than September 2021 (Table 2).
Average temperatures for the month of October ranged from 60-65°F across most of Ohio, while the northeastern and northwestern corners averaged between 55-60°F (Fig. 5). Since October 2021 was the warmest October on record for Ohio, temperatures for most of the state were significantly higher than normal, with central Ohio reaching as much as 8°F warmer than normal. The entire state was at least 5°F warmer than normal (Fig. 6).
Almost every county averaged its warmest October temperature, but Lawrence County was the warmest at 61.8°F. Ashtabula and Columbiana County tied for the coolest county, both averaging 58.6°F, but this was the 2nd warmest October for both counties (Fig. 7). Historically, the coolest October average temperature during the period was 44.7°F in 1925 and the warmest average temperature was 60.6°F in 2021 (Fig. 8).