Does A Cold Spring Mean a Warmer than Normal Summer?

I have gotten a lot of questions and comments about the connection between a colder-than-normal spring and conditions during the summer.

Several folks are convinced that a cold spring means a warm summer, mainly based on what happened last year.  

So let's look at the data and find out!

Let's start by plotting spring (March-May) temperatures over Washington State using the NOAA Climate Division dataset for the past century (through 2022).  Warmer earlier in the period, then cooling in the 1950s-1970s and then warming back to the earlier levels during the past decades.  

I then identified the top ten coolest springs.

Next, I determined the top ten coolest springs and plotted their anomaly (different) from normal (the averages for 1991-2020) temperature for the summer (July through September)-- below.   

The result?  Summer surface air temperatures were substantially cooler than normal after cool springs.

So based on climatology, there is no reason to expect a warmer than normal summer...in fact, just the opposite.

But what about seasonal forecasting models, such as the one run by the European Center?    Below is its forecast for the surface air temperature anomaly from normal for July through August.     Very close to normal conditions are being predicted.


The Canadian seasonal model, which is quite good in general, is similar to the European Center (see below).  Near normal for our region.


In contrast, the American Model (CFSv2), which generally is not as skillful, has this summer warmer than normal by .5 to 2C.

The Bottom Line:

    At this point, there is no strong reason to expect a warmer-than-normal summer here in the Northwest.  Climatologically, cold springs do NOT tend to be followed by warmer than normal summers, if anything it is just the opposite.   The best season models show near-normal temperatures from July through September.

And I can't help but note that our seasonal forecasting skill, particularly for summers, is generally quite poor.  Meteorologists have come a LONG way with short-term weather prediction, but our seasonal prowess is something we need to be very humble about.  😇


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