Does it really rain every Thursday?
It’s another rainy day across the Commonwealth [of Pennsylvania]. It’s also Thursday. A friend asked me this morning, “is there some sort of meteorological reason why it always rains on Thursdays?” I recalled it did seem to rain on a good number of Thursdays. But how many exactly?
I consulted a handy calendar to get the dates of Thursday going back to the beginning of the semester (actually, the Thursday before), which was a total of 12 Thursdays. I then went to the National Weather Service’s Climate Information Site and, using the Preliminary Monthly Climate Data, determined exactly which Thursdays it rained. The results are displayed below:
| Date: | 8/19 | 8/26 | 9/2 | 9/9 | 9/16 | 9/23 | 9/30 | 10/7 | 10/14 | 10/21 | 10/28 | 11/4 |
| Rainfall Amount (in): | 0.00 | 0.00 | 0.00 | 0.00 | 0.21 | 0.00 | 3.91 | Trace | 0.23 | 0.03 | 0.00 | Ongoing |
| Other Details: | Trace day after | .42 day before | .62 day before | Trace day after | Trace day after | Trace day after |
Some notes about the data:
- I included the days where there was rain before or after just to factor in “cognitive” concerns (such as people thinking it rained on Thursdays when there was rain on days around it).
- While, ultimately, I am concerned about when it rained in State College, PA, that city is not available from the NWS Climate Information page. Therefore, these values come from Williamsport – the closest location.
What do the results ultimately yield? Since the beginning of the semester it has rained on exactly half of all Thursdays, the bulk of it between September 30 and October 21!