It’s only early September, but residents of northern Minnesota could wake up to frost.

The National Weather Service says temperatures Monday night will drop to the mid 30s.

Rural areas of southern Minnesota also could see patchy frost. Lows there will be in the upper 30s to low 40s.

It’s probably a good idea to cover your tomatoes and bring in plants sensitive to frost.

The cooler weather resulted in early Monday temperatures ranging from 36 in Hallock to 52 in St. Paul. Embarrass, in northeastern Minnesota, reports an overnight low of 33.

The weather service says Tuesday will be mostly sunny and warmer, with highs in the mid 60s to low 70s.