Generally the western and southern half of the USA has an overall warmer weather, as compared to the eastern and northern half. Eastern/Northern half is extremely cold in winters accompanied by heavy snowfall, and has pleasant summers whereas the Western/Southern part has extremely hot summers and comparatively tolerable winters.
Northwest Pacific is the wettest part of the country. Here the summer months are pleasantly warmer but never too hot. You can see fogs along the coast during the warmer weather, which disappears by the mid-day.
Mid/South Pacific Rockies have generally dry and delightful summers. There are very few places in California which experience snow, mostly all the cities have quite tolerable winters. Midwest region is moderately dry. Precipitation occurs mainly in late Spring and early Summer. All have excellent Summer weather, but the Winters are bitterly cold, with quite a lot of snow and heavy chilly winds.
Northeast area is moderately rainy. In winter, the area experiences a heavy snow and freezing rain. Summers are usually pleasantly sunny and warm. The fall is especially beautiful in wooded areas. Southeast is very hot and dry in summers. The entire area experiences moderate rains fairly evenly throughout the year. The Spring, Summer and Fall seasons are all very pleasant. Some snow and freezing rain will fall in Winter, but, for the most part, the winters are quite mild and short lived.
Southwest is unbearably hot and humid in summers. This is the hottest and high rainfall region of the US. The winters are generally short in duration, but some freezing rains do occur. The spring and fall seasons are quite long and temperatures are generally excellent. The summers are very hot with temperatures.