National Weather Service Weather Forecast Office

As we begin the month of December, we mark the conclusion of meteorological fall and the beginning of meteorological winter. The fall was highlighted by large swings in weather patterns over central Indiana, with warm and dry conditions through September giving way to unseasonably cold and very wet weather for much of October. Warm and dry conditions returned through the first three weeks of November, with colder air arriving over the last week of the month. The following is a summary of weather conditions experienced in central Indiana during the months of September, October, and November 2009.

 

Other than a low maximum temperature record of 44 degrees being tied at Indianapolis on October 17, no temperature or precipitation records were set during the fall.

 

 

The fall of 2009 was tied for the 47^th warmest fall ever, with an average temperature of 55.8 degrees. The normal fall season average temperature is 54.6 degrees, making fall 2009 above normal by 1.2 degrees. The average temperature was nearly identical to the fall 2008 average of 55.9 degrees.

 

The fall of 2009 was characterized by wide swings in weather patterns from month to month. September was warm as a persistent area of high pressure remained across the region for the first half of the month. Temperatures cooled during late September, with a more significant pattern change to a colder, wetter pattern for most of October. Milder weather returned for the last ten days of October, and persisted into the first half of November as high pressure returned.  Colder and more seasonable temperatures arrived at the end of November.

 

There were 14 days of 80 degrees or warmer during fall 2009, all occurring in September. A normal fall would expect to see 16 days of 80 degrees or warmer. This was the first time since 2006 that temperatures did not reach 90 during the fall season. The cool temperatures experienced for much of October led to an unusual occurrence of the highest November temperature at Indianapolis (72) being warmer than the highest temperature during October (70). This phenomenon has only occurred in 1977 and 1987 prior to this year. Furthermore, Indianapolis experienced more days at or above 70 degrees (2) in November than in October (1). This had only happened in 1888 previous to this year.

 

  

 

 

 

 

 

 

 

Rain during the fall of 2009 came in spurts, as a drier than normal September was followed by the 9^th wettest October on record. This was then succeeded by the 9^th driest November on record. 

 

Overall this was the 70^th driest fall on record. The total rainfall for Indianapolis this fall was 8.61 inches. The normal rainfall total for fall is 9.25 inches, which made this fall below normal by 0.64 inches.  There were wide variations in precipitation totals over the three month period, with southern and western sections of central Indiana generally seeing the most rainfall. One exception to this was at Terre Haute, where just 5.85 inches of precipitation fell, or 4.37 inches below normal. Even more interesting, Bloomington received nearly double the rainfall during the period (11.60 inches) than Terre Haute.

 

Indianapolis is already assured of finishing above normal for precipitation in 2009 as the total for the year is currently at 45.36”, or 7.44” above normal through November 30.

 

 

 

 

 

This year, just a trace of snow was recorded during the fall season at Indianapolis. This all came on Thanksgiving Day, November 26. A normal fall season at Indianapolis would bring 1.7 inches of snowfall.

 

 

 

October 8-9: Unusual October river flooding occurred along the White River in southwest Indiana following rains of 2 to nearly 5 inches on the 8^th and 9^th.  Lowland flooding lasted less than 2 days. Flash flooding of county and state roads also occurred in portions of southern Indiana on the 9^th. 

 

 

 

The official outlook for the winter season 2009-10 (December-February) from the Climate Prediction Center, indicates a higher chance of below normal temperatures across central Indiana. At Indianapolis, the average temperature for the winter season is 29.8 degrees. A greater chance of below normal precipitation exists across central Indiana through the winter.   At Indianapolis, the average precipitation for the winter season is 7.92” and the average snowfall is 21.8”.