North Platte has a continental climate with cold winters and hot summers. The most comfortable time to visit is late spring (May–June) or early autumn (September–October), when temperatures are mild and the light on the surrounding plains is at its best.
Summer (July–August) sees temperatures regularly above 35°C and occasional severe thunderstorms, though neither will prevent you from doing what you came for. Winter temperatures drop well below freezing and I-80 occasionally closes in blizzards — if you are driving through in January, check road conditions before leaving.
The Nebraskaland Days festival in June is the city's main annual event, centred on a rodeo and Buffalo Bill–themed celebrations. It draws a crowd and books out accommodation, but it is also one of the more authentic western-tradition events you can find.