The Dust Bowl drought continued for multiple years. In 1934 Oklahoma received less than 10 inches of moisture of any kind. Then 1935 was also much drier than normal. Then 1936 was also a severe drought with less than 10 inches of total precipitation.
Bear in mind, periodic droughts were and are normal for much of Oklahoma. It was the wheat speculation combined with ignorant farming practices that caused the Dust Bowl. First, higher than average rainfalls and high wheat prices encouraged farmers to break the drought-tolerate Buffalo grass sod in massive, reckless swathes. Even so, the cover the wheat crop provided would have prevented the Dust bowl, but the wheat market crashed and the absentee owners didn’t know or care care that the land needed cover. Suprlus wheat was piled in great heaps with no place to store it, so they didn’t put more in the ground (or were unable to). So when the 1934-1936 droughts rolled around, there was nothing holding the dirt down.
Really interesting book, available from Kindle Lending if you’re a Prime member The Worst Hard Time.