Hamilton is set to see another blast of unseasonably cold temperatures starting this weekend, just days before the official start of spring. 

The city's medical officer of health has issued a cold alert, which will come into effect early on Sunday morning. 

The warning is issued anytime the current or expected temperatures fall below –15 C or –20 with the wind chill. 

Hamiltonians woke up on Saturday morning to above-zero temperatures and what looked like a spring thaw. 

But a cooling trend began in the morning, bringing values down below the freezing mark by the afternoon, is expected into Sunday morning. 

An overnight low of –15 C in the forecast for Saturday night. With the wind chill, it could feel as cold as –23 C, said Environment Canada meteorologist Wei Zhang.

Bright skies and a high of –6 C are in the forecast for Sunday. But temperatures are expected to drop as low as –17 C early Monday morning, threatening a 22-year-old weather record.

On March 17, 1992, the mercury fell to –14.7 C at Hamilton International Airport. That was the coldest temperature measured at the site on St. Patrick’s Day since the weather station open in 1959.

Winds of around 20 km/h could make Monday morning's deep freeze feel as cold as –25 C.

Temperatures are expected to climb starting on Monday, with a high of –4 C expected for the day. A mix of sun and cloud and a high of 2 C are in store for Tuesday. And the forecast calls for snow or rain and a high of 2 C on Wednesday.

Can Hamiltonians expect to say goodbye to wintry weather when spring officially starts on Thursday?

"I’m wouldn’t be surprised if there was another cold event before the end of the month," Zhang said.