MLB regular season postponed/cancelled games by month for the 2009–2019 and 2021 seasons.
Code:
MLB Regular Season
Postponements/Cancellations by Month
Mar Sep
Apr May Jun Jul Aug Oct Total
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2009 12 8 6 3 2 6 37
2010 2 7 3 1 3 5 21
2011 17 15 2 2 11 4 51
2012 8 2 2 0 2 7 21
2013 18 8 6 3 0 2 37
2014 18 5 4 2 3 3 35
2015 6 5 8 4 1 14 38
2016 11 7 1 2 2 3 26
2017 12 15 1 2 6 3 39
2018 28 7 4 5 2 9 55
2019 15 9 4 4 3 4 39
2021 22 15 8 17 7 6 75
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Total 169 103 49 45 42 66 474
35.7% 21.7% 10.3% 9.5% 8.9% 13.9% 100.0%
57.4% of postponements over these seasons occurred in the first two months. 2018 had the most in Mar/April. 2021 had an usually wet July, while 2015 had a wet September.
The next question would be the number of games made up by month.