I live north of Enid, too and can't imagine living anywhere else. The thing that you will get into here, is there is alot of land in cultivation, so you would have to plant grass. The fellow I buy my hay from, sprigged every acre he has to Midland 99 bermuda grass. He gets astronomical amounts of hay off of it every year, so I know that you could graze it pretty hard, but you would sure want to control weeds, as well as fertilize, fertilize, fertilize. He claims that when he started sprigging, he was planning on grazing stockers on there at a rate of 2 head/ acre. So I would bet that you could run 1 cow/3 acres year round.
Springtime is when we get the bulk of our rain for the summer. It also rains 2-3 times during wheat harvest which is in June (count on it), to kinda help out. By the 4th of July (most years) we start getting the 100+ degree weather, and rainfall is just a memory. Then by Labor day the weather usually breaks, and we can have pretty nice weather along with moisture until the middle of November when we get our average first frost. About 4-5 years ago, I had to mow my yard on Thanksgiving weekend. We didn't get a killing frost until the 2nd week of December.
I think it was Will Rogers that said "If you don't like the weather in Oklahoma, wait awhile". That saying holds true numerous times per year around here.