The NWS Climate Prediction Center released their latest outlooks for March, April, and beyond. So far, March has been cooler and drier than normal. The statewide average temperature was 36.8 degrees, which is about a degree below normal, while the statewide average precipitation was 1 inch, about 70% of normal.
Rest of March: there is an increased chance that the rest of March will be both colder and wetter than normal, according to the NWS forecast that extends out to 14 days. Here are the maps for the 8-14 day period. The 6-10 day maps are nearly identical. The expected colder and wetter conditions are widespread across the Midwest.
April: the outlook for April resembles the waning stages of a typical La Niña event. The southern third of Illinois has an increased chance of being warmer and wetter than normal. There are no strong climate signals for the rest of the state.
April-June: the outlook for April-June shows Illinois and much of the Midwest with an increased chance of being both warmer and wetter than normal. That would be pretty much in line with the conditions we have seen in previous April-June periods. Seven out of the past eight April-June periods have been warmer than normal; six out of eight have been wetter than normal.
July-September: the big black hole of uncertainty in the central US is due to a lack of guidance from the models and the climate trends. The eastern half of Illinois has a slightly increased chance of being warmer than normal from July through September. There are no strong climate signals to provide any guidance for rainfall in Illinois. This is a very common situation with the outlooks for Illinois and the Midwest during summer because rainfall at this time of year is often driven by short-lived features (e.g., passing cold fronts) and local conditions (e.g., too much or too little soil moisture).
Historically, there are no strong trends in rainfall for this period. However, there is a lot of year to year variability. The same is true for the average temperature. We have noticed a decrease in the average daily high temperature in recent decades while the daily average low temperature has increased. The two trends essentially cancel each other out. However, higher nighttime temperatures can be detrimental to crops, livestock, and humans because it impedes the recovery from the daytime heat. Several studies have noted increases in summer humidity. That will be a subject for a separate post.