Temperatures fell to 37 degrees early Monday morning at Baltimore/Washington International Thurgood Marshall Airport, tying a record set in 1973.

It was the first time Baltimore dropped to the 30s in a month -- the last time, BWI hit 38 degrees April 17.

Normal lows are in the lower 50s by this time of year. Lows the rest of the week are expected to inch closer to that level, but are expected to stay a few degrees below normal in the upper 40s to around 50 degrees.

Highs are forecast as much as 15 degrees below normal, in the upper 50s and lower 60s through Wednesday.

May temperatures are running about 4 degrees below normal, with average highs around 64 degrees and average lows around 50 degrees. By this time last May, Baltimore had hit the 80s on 11 occasions.

Unseasonably cold weather is spread across much of the eastern half of the country. Temperatures were forecast to stay 10 to 25 degrees below normal across the Midwest, Great Lakes and Ohio Valley states. Freeze warnings were in effect for parts of the Midwest and Great Lakes.