What is important is not the general weather but the weather on Test days.
Someone has counted up the number of days washed out in Tests up to 2004.
https://community.netweather.tv/topic/16950-number-of-days-washed-out-for-test-matches-in-engl/
Old Trafford: 29 days washed out.
Headingley: 12 days washed out.
Pretty conclusive though someone might like to do further research to see if the same trend continued after 2004.