The Plains & ridges in the Rockies (especially Wyoming) are obviously the windiest places in the lower 48 when you look at the average wind speeds for the year at 262'.
Interestingly, the average wind speed at that level is the highest in Benton County than any area east of central Iowa to eastern Kansas.
At 262', the highest average wind speed is centered over Benton County. This also covers southern Newton, southwestern Jasper, southwest White & northwest Tippecanoe counties.
Another area of enhanced wind is located from northeast Fountain to southern Tippecanoe, northern Montgomery to Clinton counties.
The average annual wind speed at 98' is highest in Benton County & southern Newton-Jasper to southwest White, northwest Warren & northwestern Tippecanoe counties.
Another area of enhanced wind occurs southern Tippecanoe to Clinton counties.
These two areas of enhanced wind correlate exactly to "The Grand Prairie" & then what pioneers called "Twelve Mile Prairie". Twelve Mile Prairie was actually more like 40 miles long, but it averaged 12 miles wide. It ran from northeast/east of Attica all the way to Frankfort, then Sharpsville. Forest, in Clinton County, was named for it being where the forest began on the edge of the prairie as one traveled east & northeastward toward Kokomo.
This tallgrass prairie map is from Transeau & Gordon (1935) as shown in Robert Betz' paper "The Prairies of Indiana" (Department of Biology, Northeastern Illinois University):
Areas of large prairie were typically flat with a lack of any natural surface streams for firebreaks, especially those with any north-south orientation to disrupt usually eastward-advancing wildfires.
These areas also tended to be windier owing to their lack of tree cover & an extension of more of a tallgrass prairie climate from Illinois & Iowa (with peak rainfall in summer & bit drier weather compared to the region in fall & winter to early spring [on average]).
Prairie fire pic from Jen Benson Hughes: