OTTAWA -- It's going to be a dry start to the week in Ottawa, at least compared with the rain we saw on Sunday.

But it's going to get cold Monday night. Like, freezing cold.

Environment Canada is calling for a mix of sun and cloud on Monday with a high of about 15 C.

But at night, the temperature will take a plunge: all the way to 1 C, with a patchy frost.

A frost advisory is in effect for Ottawa.

"Patchy frost is expected overnight and into Tuesday morning as temperatures drop to near or just below the freezing mark, the advisory from Environment Canada says. "Cover up plants, especially those in frost-prone areas. Take preventative measures to protect frost-sensitive plants and trees."

Things are expected to warm right back up on Tuesday, which will be sunny with a high of 17 C.

And on Wednesday, summer-like weather returns. The expected high of 24 C with a mix of sun and cloud.

The warmer temperatures will stick around on Thursday, with a more seasonal high of 20 C, but there's a 30 per cent chance of showers.