Eastward warming and increased sunshine will highlight the nation's weather at midweek, in time for St. Patrick's Day.

Some of the best weather, plentifully sunny nearly everywhere, will span the East and the Upper Midwest. Temperatures will reach the 50s to about 60F, or significantly above normal.

Across the South, meanwhile, it will still feel a bit cool after a rather cold start. However, aside from a few showers in the Mississippi Valley, dry weather with partial sunshine will predominate.

The picture of plentiful sunshine and minimal precipitation will replicate over the West. Strong sunshine will afford the Desert Southwest the nation's warmest weather with highs well into the 80s over southern Arizona to inland valleys of Southern California.

A weakening cold front will bring spotty rain and mountain snow to the interior Northwest as it chills Seattle and Portland.

Story by AccuWeather.com Senior Meteorologist Jim Andrews.