Frequency of warm nights in the Twin Cities on the rise

Now that the 2012 summer is behind us, those of us in the weather business like to examine its statistical character. Paul Huttner has pointed out that the 30 days with temperatures of 90 degrees F or higher in the Twin Cities is the most since 1988. Another trend in temperature worth noting is the number of warm nights. Generally speaking those living without air conditioning have difficulty sleeping when the overnight low does not drop below 70 degrees F.

In 2012 the Twin Cities recorded 23 nights when the overnight low did not drop below 70 degrees F. This was the 7th year since 2001 that 20 or more nights have been so warm. A high frequency of such warm nights used to be more infrequent. But, needless to say both urbanization of our local Twin Cities environment combined with signals of climate change may be contributing to this higher frequency of warm nights. Here is a look at the years when 20 or more nights have not dropped below the 70 F mark going all the way back to 1871:

1916 24 nights

1921 25 nights

1931 24 nights

1933 20 nights

1935 25 nights

1936 26 nights

1937 29 nights

1941 21 nights

1949 20 nights

1955 22 nights

1959 21 nights

1983 21 nights

2001 22 nights

2002 21 nights

2005 22 nights

2007 20 nights

2010 22 nights

2011 24 nights

2012 23 nights

  • Luke Van Santen

    Can you share the rest of the data? How many nights above 70 were there in 1872? or 1917?

    Thanks!