When do snakes come out of hibernation?

i live in Texas and i have been a snake hunter for 10 yrs. i am 19 and i do research on road temps. and elavation etc. we have more of a variety of snakes in Tx. than in any other state i have also worked at a zoo as a volunteer in the herp department as a kid for 4 yrs. but primarily the climate and weather patterns depends on what snakes will be out either field herping or road cruising rural highways i find a assortment of snakes each time i go which is almost everyday in the summer, for good advice do the research on the exact snake you are finding or looking for in your region to decide when to catch them also use your phone to see what counties in your area have the best weather climate to catch that day do the research and you will find what your looking for half of the time but dont be discouraged if you dont see anything all the time i have gone two weeks strait and not found a thing then randomly one of those days i hit a honey hole any ways i have a lot of info. on what to do or how to find snakes just from experience alone so do the research and who knows maybe you will find what your looking for.....

im in ilinois and its like may should i start looking for them?