Seasonal Climate Summary: Summer (September-November 2024)

Provided by the State Climate Office of Ohio, a collaboration of the Byrd Polar and Climate Research Center, Geography Department, and OSU Extension with support from Energent Solutions.

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Temperature and Precipitation

During the fall season, Ohio noted above-average temperatures and variable precipitation patterns. Statewide, average temperatures were 2–4°F higher than normal for the season (Fig. 1a). Precipitation totals ranged widely across the state, with most areas receiving between 5 and 12.5 inches. Isolated regions reported as little as 3–5 inches, while others recorded totals exceeding 12.5 inches, with some areas surpassing 15 inches (Fig. 1b). Precipitation departures from the norm varied significantly. Northern Ohio experienced deficits of 1–6 inches below normal, whereas southern parts of the state recorded surpluses ranging from 0 to more than 5 inches above normal (Fig. 1c). Similarly, the percent of normal precipitation map highlights a distinct contrast: northern areas received just 50–75% of their typical rainfall, while the southern regions saw 100–150% or more of their average (Fig. 1d). A notable factor contributing to the above-normal precipitation in southwestern Ohio was Hurricane Helene, which impacted the area in late September.

4 panel map of temperature and precipitation
Figure 1: Statewide departures from normal temperature (a) and accumulated precipitation (b) over the summer months at top, followed by statewide accumulated precipitation departures (c) and percent of normals for precipitation (d) at bottom. All data courtesy of the Midwestern Regional Climate Center.

Soil and Energy

The 3-month Standardized Precipitation Index (SPI) for the fall season indicated a return to near-normal conditions compared to the summer. Most areas across the state recorded SPI values between -1 and 1, with localized regions ranging from -2 to -1 and 1 to 2 (Fig. 2). Improvements in soil moisture conditions were primarily observed in November, attributed to reduced evaporation rates as daylight hours shortened. The elevated SPI values in the southern region can again be linked to Hurricane Helene, which brought substantial rainfall to this area.

3 month spi map
Figure 2: Three-month Standardized Precipitation Index (SPI) across the state of Ohio from September through November 2024, used as a proxy for soil moisture conditions. Data courtesy of the High Plains Regional Climate Center.

Above-average temperatures throughout the fall resulted in fewer Heating Degree Days (HDDs) and a slightly higher number of Cooling Degree Days (CDDs) than normal (Fig. 3). This led to reduced energy demand overall, as the warmer temperatures decreased the need for building heating.

Degree Day map and chart
Figure 3: (Left) Total September-November heating & cooling degree days. (Right) Corresponding Ohio Climate Divisions. Data courtesy of the Midwestern Regional Climate Center

Notable Events

During the fall season, drought conditions in Ohio showed significant improvement, particularly in November. The most severe drought categories, D4 and D3, were eliminated, with the highest remaining classification now being D2. The total area affected by drought (D1-D4) decreased by an impressive 52.33%. Currently, 7.06% of the state is classified as D2, 28.06% as D1, 23.76% as D0, and the remaining 41.13% is not classified as experiencing drought (Fig. 4).

Drought comparison with chart
Figure 4: Image of the comparison between the Drought Monitor Map for September 17 vs December 24. The first map shows zero drought conditions, and the second shows exceptional drought conditions based on the U.S. Drought Monitor (2000-present). 

These improvements mark the beginning of a recharge in soil moisture, which is essential for field preparation ahead of the growing season. Restoring normal soil moisture levels will reduce erosion and enhance tillage conditions for early planting. Most of these positive changes occurred during the latter half of the fall, from early November through mid-December. The key factors contributing to the improvement were increased precipitation and reduced evaporation due to shorter daylight hours. The accumulated precipitation map highlights a broad band of higher rainfall amounts stretching from southwestern to northeastern Ohio, with additional precipitation in the southern region (Fig. 5). This renewed moisture benefits farmers by initiating groundwater recharge, setting the stage for healthier growing conditions. Although it is still winter, the growing season is fast approaching, making it essential to continue monitoring soil moisture trends.

Map of accumulated precipitation
Figure 5: Accumulated Precipitation map for November into mid December. All data courtesy of the Midwestern Regional Climate Center (http://mrcc.purdue.edu).

Looking Ahead

The Climate Prediction Center’s (CPC) three-month outlook suggests a likelihood of warmer-than-average temperatures and above-average precipitation for Ohio, albeit with slight confidence. The seasonal temperature outlook indicates warmer-than-normal conditions across the state for the winter season (Fig. 6a). Similarly, the precipitation outlook projects above-average levels of precipitation statewide, also with slight confidence (Fig. 6b).

Temperature outlook map
Map of seasonal precipitation outlook
Figure 6: a) Nationwide Seasonal Temperature and b) Precipitation Outlook for September-November 2024. Courtesy of the Climate Prediction Center.

Note: these outlooks do not provide the quantity of above or below normal conditions, just the likelihood of occurrence (i.e., the probability).​

This combination of warmer and wetter conditions aligns with the current neutral ENSO phase, which often results in less predictable seasonal patterns. Typically, El Niño winters in Ohio are warmer and drier, while La Niña winters tend to be colder and wetter. The current outlook, reflecting elements of both scenarios, highlights the uncertainty associated with a neutral ENSO phase and suggests potential variability in Ohio's winter climate this year. Variations from this forecast have already occurred with multiple spells of below-normal temperatures experienced in the early parts of December.

Authors

Aiden Ridgway: Atmospheric Sciences Undergraduate, Student Assistant: Climate Services - Byrd Polar and Climate Research Center, The Ohio State University, ridgway.72@osu.edu

Geddy R. Davis: Meteorologist/Atmospheric Scientist, Program Coordinator: Climate Services - Byrd Polar and Climate Research Center, The Ohio State University, davis.5694@osu.edu

Aaron B. Wilson:  State Climate Office of Ohio, Byrd Polar and Climate Research Center & OSU Extension, The Ohio State University, wilson.1010@osu.edu