Wednesday, March 26, 2014

Large Diurnal Range

[Updated March 27, see bottom]

In weather that is quite characteristic of the time of year, valley locations around Fairbanks have seen large diurnal fluctuations in temperature in recent weeks.  Strong solar heating by day and warm temperatures aloft have produced warm afternoons, but clear skies and a 20+" snowpack have allowed for sharp cooling at night.  At the airport, the average difference between the daily high and low temperatures so far in March is 33 °F, which is towards the high end of the historical range for the time of year, but is not a record (March 2011 saw an average diurnal range of 36 °F).

The charts below show that daily maximum temperatures have been mostly above normal in the past month (+5.9 °F anomaly in the past 30 days), but daily minimum temperatures have remained mostly near normal (0.0 °F 30-day anomaly).

[Update:] Reader Eric suggested making a plot of the daily temperature range; this indeed nicely illustrates the rapid increase in diurnal range during February.


  1. To see the diurnal range you could make a band plot. The top is the high, the bottom is the low, and your favorite color is the middle. You could still include the positive s.d. for the high and the negative s.d. for the low. I think this would be a good way to see how small the range is in winter and large in spring. Now, are we going to have an early breakup or late summer...

    1. Great idea, Eric, I've added the plot.