Temperatures were forecast to sink all day Monday, and spotty light rain could turn to snow or sleet in the afternoon, the National Weather Service said.
Thermometer readings in the upper 40s at midnight were in the low 40s for the morning commute and were not expected to rise from there before sinking to the low 20s overnight.
If the rain turns to frozen precipitation, there should be little or no accumulation, the weather service said.
Tuesday was forecast to be cloudy but dry with a high in the upper 30s. Wednesday was forecast to be about 10 degrees warmer.
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ABC11 meteorologist Don Schwenneker said conditions had potential to be more unpleasant after that.
“Wednesday night into Thursday, we’ll fall down into the 30s, and I think we could see a wintry mix to snow.” Schwenneker. He did not predict whether it will accumulate, however, and the chance of precipitation was less than 50 percent.