If a football game is being delayed, chances are that there is lightning in the area. Of course, other things can prompt a delay in the game, but lightning is one of the more common causes. Simply put, lightning and stadiums don’t mix. Because lightning can have a such an impact on college football, I decided to try to add it to the climatology in some fashion.

CFB Top 20 Thunderstorm FrequencyOf course, records of thunderstorms are a little harder to come by than standard measurements like temperature and rainfall. There were several different ways to try to come up with some reasonable approximation of thunderstorm frequencies, but I settled on this data plotting website from the Iowa Mesonet. This provided a method to extract thunderstorm reports on hourly observations, which was useful because I was really only interested in the Noon to Midnight local time frame. That is, of course, because college football games are largely played at some point in that time window.

The data files that you can download are presented in time steps of weeks. I chose to look at the 13 week period from “Week 36” to “Week 48”. Exact dates vary from year to year, but in general this corresponds to the September to November time frame.

Because the data are from automated stations, in some cases it was difficult to find a reliable site in very close proximity to the stadium location. Therefore, I followed the basic principle of locating the closest automated station to the stadium that had at least 15 years of reliable data. Occasionally I had to make a subjective determination to discount certain stations, as their thunderstorm frequencies departed substantially from more reliable and well-maintained first order climate sites in the general region. The point is: while I would not take the data to be a perfect facsimile of the trends at each stadium location, I do think they are generally representative and illustrate some interesting things.

The numbers being displayed essentially are the average rate at which thunder was reported on any given hour between Noon and Midnight local time. As a simple example, consider the following averages for these individual hours from September to November in Anytown, USA: 3% of the Noon observations, 4% of the 1 PM observations, and 5% of the 2 PM observations. The average as I computed it in this exercise would be 4% for the Noon to 2 PM time frame. This should not be confused for the percentage of days in which thunder was reported, which would likely be considerably higher.

The bubbles on the map represent individual stadium locations. The size of the bubbles increases with increasing thunderstorm frequency. The color also changes from blue to orange with increasing thunderstorm frequency, to make high-frequency areas stand out more.

The bubbles on the map represent individual stadium locations. The size of the bubbles increases with increasing thunderstorm frequency. The color also changes from blue to orange with increasing frequency, to make high-frequency areas stand out.

Unsurprisingly, the results show that some of the greatest lightning frequencies are near stadium locations in Florida. All seven of the FBS Florida universities were in the top 11 overall. Almost every spot in the state experiences at least 70 days of thunderstorms per year (NWS). The rest of the stadium locations with the highest lightning frequencies in college football season all hailed from southern states.

Recommended: Interactive Map

You can access an interactive version of the above thunderstorm frequency map on Tableau by clicking here. You can filter the data by the thunderstorm frequency using the slider in the upper left.

One very important thing to add is that every single location had at least some thunder reported during the college football season! In other words even in places you wouldn’t necessarily expect to experience a thunderstorm at a college football game, it is not impossible for one to occur.
Monsoon Lightning Frequency
You may be a little surprised to see some moderately high thunderstorm frequencies in the Four Corners region of the western United States. This is largely due to what happens in September in those areas, as the North American monsoon lingers through the late summer and into the early fall. For example, Tucson, Arizona’s third rainiest month is September in which 11% of their annual precipitation falls (on average).

The map on the left from NWS Albuquerque shows lightning frequency by month in the desert Southwest. There is very little lightning activity until the monsoon ramps up in July; although the lightning activity tails off a bit in September, it is still a fairly active month across the region. This is why you see some locations in the Four Corners higher on the overall ranking of college football season thunderstorm frequency. While the total rainfall amounts in those locations may not be exceptionally high, when rain does occur it is often (but not always) accompanied by lightning during monsoon season.

Every single location had at least some thunder reported during the college football season, even in places you wouldn’t necessarily expect.

Another thing I found interesting was a slight lowering of thunderstorm frequencies along the Interstate-20 corridor in the Southeast. The frequencies in those areas are still fairly high compared to the country overall, but relative to locations along the Gulf coast and locations just north (such as in parts of Tennessee, Arkansas, and Oklahoma) the values were lower by a small margin.

For lightning safety information, you can visit the National Weather Service’s Lightning Safety Page, which includes a toolkit (PDF, DOC) for large event venues. Remember that all lightning is dangerous, and the safest place to be during lightning is indoors.