A drier pattern set in place with temperatures a bit above normal during the month of September. Rainfall totals measured only 2.20 inches in the Chicagoland area, just shy of an inch below average. Despite a few heavy rain events throughout the month, the lack of more frequent storms kept overall rainfall low for the month. High temperatures varied considerably throughout September, reaching near 90 at the start of the month to the low 60s by the end. Despite the variety of temperatures, the average high temperature was 76.0 degrees and the average low was 58.8 degrees, each 0.5 and 1.7 degrees above normal respectively. Overall, the average temperature for the month was 67.4 degrees, 1.1 degrees warmer than average.
The month started off warm, with high temperatures reaching the mid to upper 80s for the Chicagoland area (on the higher end in the city itself) for the first several days. It was generally dry for the first week of September with a few isolated minor storms both the 3rd and 4th. Following the few instances of rain, temperatures cooled substantially to the low 70s after the passing of a cold front. Below average temperatures did not hold for long, with highs warming back to the low to mid 80s beginning on the 6th with a dry period to follow. An extensive rain event impacted the area on the 11th, bringing with it rainfall totals upward of one inch in most areas, though suburbs to the north and west measured much higher. Chicago itself measured 1.45 inches of rain from the event whereas Rockford saw as high as 4.34 inches. Temperatures dropped considerably following the rain event from the mid 80s down to the upper 60s.
Two-day rainfall totals from September 11-12th. Courtesy NWS Chicago.
The middle of the month saw a week-long dry spell in the region with highs returning to the low 80s once more. Rain returned on both the 17th and 18th, with a few storms firing up the latter of the two days. Some of these storms produced ping pong ball-sized hail, particularly in the Geneva area. Temperatures cooled to below-average levels once again, though only temporarily.
Hail reports from September 18th storm. Courtesy NWS Chicago
Heat began to build beginning on the 20th as highs pushed into the mid to upper 80s, peaking near or at 90. The heat did not last long, with a strong cold front returning the area to highs in the mid 60s. These autumn-like temperatures continued through to the end of the month and, aside from some showers on the 24th and 25th, drier conditions prevailed.
Heading to central Indiana, dry wether also prevaled with monthly rainfall totals measuring 2.12 inches, 1.02 inches below normal in Indianapolis. Although the area saw a few moderate rain events throughout the month, the frequency of these and the light nature of the shower events were not enough to produce significant rainfall totals. Temperatures, for the most part, fared a bit warmer than what is typical, though high temperatures fell a bit below normal. The average high and low temperatures were 77.7 degrees (0.5 below average) and 58.5 degrees (1.1 above average) respectively. The average temperature for the entire month was 68.1 degrees, 0.3 above normal.
The month started off warm in the Indianapolis area with summer warmth lingering into the first several days of the month. High temperatures reached into the mid 80s for both the 1st and 2nd with dry conditions prevailing. Highs began to cool slightly in the days that followed as a few showers moved through the vicinity on the 3rd, some bringing minor flooding, primarily south of the metropolitan area.
Some heat returned into the second week of the month as highs returned once more to the upper 80s by the 10th, with conditions remaining mostly dry. A passing cold front on the 11th brought with it the next risk for precipitation, with temperatures cooling substantially into the upper 60s in the days that followed. Locally heavy rain produced upwards of half an inch to some areas, with Indianapolis itself measuring 0.72 inches with the day’s storms, marking the wettest day of the month for the city.
The area saw a week-long dry spell in the middle of the month as temperatures rebounded back to the low to mid 80s, remaining fairly steady thereafter. Showers and storms on the 19th brought back another round of moderate rainfall, though temperatures remained consistent in its wake. A warm front passing through the area on the 20th pushed temperatures up some, topping off in the low 90s on the 21st–the warmest day of the month.
Autumn arrived on time with seasonable temperatures returning for the final third of the month as most days remained dry aside from a few showers on the 24th. Highs steadily cooled into the end of the month, falling to the low to mid 60s as dry conditions held out through the month’s end.
The overall pattern for September varied considerably throughout the state. Areas to the south around Cincinnati, were notably drier than normal, whereas locations further north saw plenty of rainfall, with Columbus ending the month on par with normal. Focusing on Columbus, 3.14 inches of rain fell during the month, which is what is expected for this time of year. Temperatures varied a bit from normal, with the average high of 76.5 being 1.3 degrees below normal, whereas the average low of 58.0 was 1.5 degrees above average. The average overall temperature was 67.3 degrees, only 0.1 above normal. Cincinnati measured 1.94 inches of rain, 1.17 inches below average. The average high temperature was 77.6 degrees (1.3 degrees below average), average low was 58.6 degrees (1.3 above normal), and the overall average temperature was 68.1 degrees, equal to normal.
Dry weather, coupled with warmer temperatures, started off the month of September for Ohio. The high temperatures on the 1st tied with the 21st for the warmest day of the month for Columbus (reaching 87 degrees) before cooling slightly in the days that followed. Rainfall on the 3rd started a wet period that lasted several days, with areas to the north seeing higher rainfall totals. Columbus recorded its wettest day of the month on the 5th with 0.81 inches measured. Dayton also saw its highest rainfall total of the month, recording 1.20 inches the same day.
Rainfall from September 5th event. Courtesy NWS Wilmington.
Temperatures held rather steady through the second week of September with highs in the low 80s. Conditions were dry through this period, with the next rain event returning on the 11th. This event proved to be the heaviest for the month in the Cincinnati region, measuring 0.55 inches of rainfall.
Another dry spell returned into the second half of the month with temperatures remaining a tad above normal for this time of the year. A few showers returned on the 19th and again the 21st, with the latter of the two days bringing more moisture to areas further north. A brief warming trend also occurred during this time, with highs reaching the upper 80s in northern areas and as high as 93 and 94 in Cincinnati and Dayton, respectively.
After a few days of isolated showers (more so in northern areas), dry conditions persisted through the rest of the month. Temperatures gradually cooled to the low 60s before warming a bit back to near 70 by the month’s end.