Around Tulsa a fairly typical winter day might be a high around 40 and a low in the mid 20s. But plenty of non-typical days occur, too, on both sides of that. So there are some cold spells and some warm spells. We haven't been getting enough snow or ice lately to matter; occasionally an inch or three; but I can recall years when we'd get 16" in a week or a big ice storm.
NW OK and the panhandle is higher elevation and notably colder; you don't want to go there, for sure.
Maybe look at things about 300 miles farther south, in Texas or New Mexico, in low elevations. Like someone said, check weather sites like weather.com or wunderground.com for seasonal averages/highs/lows through the winter months.