The Relationship Between Temperature and Fall Cases – A Case of Three Regions

Fall temps are negatively correlated with COVID-19 cases. As it gets colder, people spend more time indoors, where the virus is more easily spread. Since Fall began COVID-19 has been surging again, but still varies dramatically by region. The Midwest is the hardest hit region. Meanwhile, cases in the Northeast are on the rise, but still lower than any other area. Looking at a trend line that takes this into account, we see a decent fit – over half the variation can be explained by the average Fall temperature for a state (expressed in degrees Fahrenheit) along with three regional categories (Midwest, South and West combined, and Northeast. See the graph below.

The y-axis is the number of new cases in the last week per 1,000 people. These numbers are much higher than similar numbers during the Summer. North Dakota is the worst, with over 11 new cases per 1,000 people. More than 1% of the population in the state was confirmed to have contracted COVID-19 in just one week!

Note that there is some overlap between regions. Rhode Island is the worst Northeast state. Its high population density may be a contributor. Given its small size, just one or two super spreader events could make a difference. Colorado has the highest number of new cases relative to population in the West, and Oklahoma and Tennessee are the worst in the South.