Highlight: Summer 2021 Cooling Degree Days.
Discussion: The Climate Impact Company initial selected cities forecast for 2021 cooling degree days is issued today. The forecast indicates this year’s forecast versus last two years and compared to the 10-year and 30-year climatology. The climatology is current (through previous year). The preliminary outlook indicates MAY-SEP 2021 is hotter than last year as the average of the U.S. cities CDD forecast is about 112% of the 30-year normal compared to just-under 109% last year (Fig. 1). Meteorological summer (JUN/JUL/AUG) is not quite as hot as last year. The U.S. cities consensus forecast for 2021 is just-over 114% of the 30-year normal compared to just-over 116% last year. The three warmest anomalous locations for MAY-SEP 2021 are Rochester and Albany, NY plus Cleveland, OH. The least hot 3 locations are Sacramento, CA; Charleston,, SC; Houston, TX.
Fig. 1: The consensus of U.S. cities monthly CDD forecasts compared to last year.
The population-weight CDD forecast is less aggressive. The MAY to SEP 2021 monthly ranking (of the past 20 years) indicates a hotter result for summer 2021 versus last year (except for August). However, the rankings are generally middle-of-the-road given the 20-year climatology (Fig. 2). The preliminary outlook is likely to trend hotter if the mid-spring soil moisture regime trends drier.
Fig. 2: U.S. population weight CDD forecast rank for the past 20 years compared to last year.