From the NWS in Indianapolis...
April 2007 will be a month long remembered for its persistent unseasonable chill for much of the early part of the month. This was in sharp contrast to last month, which was the 7th warmest March ever. The following is a summary of the weather conditions observed in Indianapolis during April 2007.
The average temperature for the month of April was 50.8 degrees. This was below the normal April value of 52.0 degrees by 1.2 degrees. This was the coldest April since 1997, when the average monthly temperature was 48.3 degrees. Interestingly, every April since 1997 had been above normal for temperatures before this year. April of last year was almost 7 degrees warmer than this year.
The month was characterized by an extended period of late winter chill from the 4th of the month through the 19th. One day during that period saw temperatures above normal. 7 days in a row experienced overnight low temperatures below the freezing mark in Indianapolis. Highs remained in the 30s for 3 days in a row, with April 7 marking the peak of the cold wave. With a high of 32 and a low of 23, the 7th set a record for the coldest high temperature ever recorded on the date. It tied for the 7th coldest day ever recorded in April in the Indianapolis area.
It was the most intense April cold snap in Indianapolis since 1982, but remarkably the whole month only finished out below normal by 1.2 degrees. This was due to the extreme warmth of the first three days of the month, as well as a return to well above normal weather the last few days of the month. The last day of the month brought the only high temperature of 80 degrees or above. March of 2007 saw 3 days with highs in the 80s. Since 1871, only 5 years have occurred when March had more temperatures in the 80s than April.
April 2007 saw 3.30 inches of precipitation measured at the Indianapolis International Airport. This value was below normal by 0.31 inches. This ends the streak of 8 consecutive months with above normal precipitation. The last month below normal for precipitation at Indianapolis was August of 2006.
While April of 2007 experienced a monthly total of just a Trace, the month was remarkable in the fact that 9 days during the month experienced at least flurries. On average only 2 days in April will experience snow. April 4-9 saw six consecutive days with a trace of snow, tying the longest such streak of its kind.