Do windshield wiper blade replacement problems track average relative humidity across states?
Across U.S. states, NHTSA owner complaints about windshield wiper blade replacement run higher where average relative humidity is higher, after adjusting for the makes sold in each state. This is an association across states, not proof that average relative humidity causes this repair.
State reports of this repair against average relative humidity, one dot per stateEach dot is a state: how much more (or less) than expected this repair is reported there, adjusted for the makes sold in the state, against its average relative humidity (percent)
How to read it: Each dot is a state. Further right means more average relative humidity (percent); higher up means more complaints for this repair than expected (1.0 is average). If the dots climb to the right, reports of this repair rise with average relative humidity (percent).
What it shows: States with more average relative humidity (percent) tend to sit higher on the chart across 42 states: a pattern in the data, not proof of cause.
Data: NOAA NCEI U.S. Climate Normals 1991-2020 (hourly), relative humidity derived by CalcScrape, joined to NHTSA owner complaints, downloaded 2026-10-06 · 42 states. Chart: CalcScrape · calcscrape.com
The 10 states with the most average relative humidity (Florida, Louisiana, Mississippi, Iowa, Delaware, Michigan, Indiana, Minnesota, Alabama, Georgia): reports of this repair run 21% above what the makes sold there would predict, and 7 of 10 are above expected. The 10 with the least (Arizona, Nevada, Utah, Colorado, Idaho, California, Kansas, Texas, Oklahoma, Nebraska): 31% below, and 2 of 10 are above expected.
Exceptions: Florida, Louisiana and Georgia are among the highest in average relative humidity but report below expected.
Split the states into thirds: the third with the least average relative humidity runs 14% below what the makes sold there would predict, the middle third 17% above, and the third with the most 25% above. Most of the average relative humidity effect sits between the lowest and the middle third.
For average relative humidity, after allowing for the 1562 comparisons we ran, luck alone would produce a pattern this strong about 1 time in 17. Take out any single state and the average relative humidity pattern still holds.
Weak spot: compare only states with similar elevation range from lowest to highest point and the pattern keeps about 41% of its strength, so part of it may come from elevation range from lowest to highest point instead of average relative humidity.
Humid air keeps metal and electrical connections damp, which speeds corrosion and electrical faults.