We have been bombarded this week with claims that the last 12 months were the hottest on record in the US. I can’t verify that claim yet, but I did calculate the same metric through the end of 2011.
The table below shows the top 25 hottest twelve month periods in the USHCN daily raw temperature database, through the end of 2011, which is the last date available. Records only get counted if they have valid data for the previous 12 consecutive months.
All of the 25 hottest twelve month periods occurred before 1936, except for one in 1998.
Month Year 12 Month Average Temperature 1 1885 55.778 11 1934 55.4316 12 1884 55.3907 8 1934 55.3385 11 1884 55.3222 10 1884 55.2937 3 1935 55.2907 2 1885 55.2879 12 1921 55.2135 7 1934 55.2126 10 1934 55.1559 12 1934 55.1296 11 1921 55.1279 12 1931 55.1152 1 1932 55.1064 5 1934 55.1029 3 1885 55.0813 2 1935 55.071 6 1934 55.0658 2 1932 55.0404 9 1934 55.0215 12 1998 55.0111 5 1932 54.9886 9 1921 54.9852 4 1935 54.9837
The table below shows the top 25 hottest twelve month periods in the USHCN daily raw temperature database, through the end of 2011, which is the last date available.
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If the table shows “12 month periods, what is the row on the left under “month”?
The last month of the twelve month period