More on April

As Corey noted in the April summary, this was 13th warmest April of record. This was mostly due to the persistence mild weather, with the warmth mid-month being the only really outstanding daily anomaly. Here's a plot of daily high temperatures in April, normals and the daily departure from normal. From the 18th through the 29th there was hardly any daily to day change in the actual high temperature. However, because normals are rising steadily, overall the departure from normal lowered with time.

And below is a plot of the mean April temperatures in Fairbanks over the past century. The linear regression for the full period 1905-2012 (not plotted) shows an increase of about 5 degrees AND is statistically significant. However, nearly all of that trend has come since the PDO shift in 1976. There is no significant trend from 1905 to 1976.