Having lived in Lincoln myself I can tell you that it is pretty much impossible for the weather to be predicted more than 48 hours in advance. We used to just laugh that they would do a 5 day forecast on the news, because it was just wrong so often.

So, prepare for hot and humid, but be ready for wind, rain, hail, tornado, clouds, drought, flood, locusts, or a beautiful morning with corn as high as an elephant's eye (I know it's not Oklahoma).