Early October: How Cold Was It?

You weren't imagining it if you thought the September 28-October 18 cold snap in Lincoln was a sudden blast of mid-winter weather.

Statistical analysis reveals it was an unprecedented string of cold days for that time of year, with a 1 in 200 probability of occurrence, said Ken Dewey, a professor of applied climate science at the University of Nebraska-Lincoln's School of Natural Resources. He compared temperatures for all of the September 28-October 18 time periods since 1887, when records were first kept, and found that the average high temperature of 56.4 degrees Fahrenheit for this year was the coldest. It was 3.6 degrees colder than the next coldest year.

"The mean daily temperature – the half-way point between the high and the low – fell below normal on September 28 and did not get back to normal until October 18," Dewey said. "That was 21 days."

On some of those days, the daytime high temperatures were lower than the normal low temperatures. Dewey noted that on October 10, the high for the day was only 38, a full 32 degrees below normal, and that the October 10 snowfall was the third earliest for Lincoln, and was in contrast with recent years when the first snow hasn't come until late fall.

Three daily temperature records were set during the 21-day cold snap: a record low of 29 degrees Fahrenheit on October 4 (tied previous record of 29, set in 1999), a record cold high of 38 on October 10 (old record was 41, set in 1987), and a record cold high of 40 on October 11 (old record was 47, set in 1946).

For more information, please contact Ken Dewey, Climatologist, UNL School of Natural Resources, 402-472-2908, kdewey1@unl.edu.

Writer: Kelly Smith, School of Natural Resources, 472-3373, ksmith2@unl.edu.