JANUARY WAS ONE LONG FREEZE-THAW CYCLE
Ottawa’s third-warmest January in 80 years has just come to an end. But the real news was that the temperature kept hopping up and down across the freezing point, jumping back and forth like a sugared-up three-year-old. “I bet you have potholes,” said David Phillips of Environment Canada’s Toronto office. Yes, David. Ottawa had filled 254,200 potholes this season as of mid-January, writes Tom Spears.
TEMPERATURES
The average high for January was -1.8 C, higher than the normal -5.8 C. The average overnight low was -9.4, compared with a normal -14.8 C.
Combine those, and January was about five degrees above normal.
In 80 years, only 1990 and 2002 were warmer in January. We had five days when the temperature dipped below -20 C. Usually we get about nine such days.
The funny thing is, it started with a four-day cold spell before the pendulum started to swing.
Phillips says we had five distinct periods of thaw during the month — stretches of two, three, one, five and four days.
On the whole they weren’t dramatic thaws of the kind that tricks plants into thinking it’s spring. The temperature typically
climbed a couple of degrees above zero, and then dropped.
“There were 13 days, sort of maple syrup days, when the temperature got above freezing in the day but below freezing at night. That’s more than double the number of freeze-thaw days.”
This is the weather that causes potholes as groundwater freezes and expands, then melts, then repeats. When water turns to ice its volume expands by nine per cent.
Phillips says your January heating bills may be a surprise after a mild month, because there was very little sun to warm us, especially in the second half of the month.
The weather office does not measure hours of sunshine, but it does record clear and cloudy weather (at night as well.) In the final 15 days of January, 10 were entirely cloudy. That’s a lot of grey.
We had 10 days in January with at least an hour of fog. Seven days had at least an hour of freezing rain. We had some ordinary rain as well.
“It was almost a buffet of weather types, but the one thing toward the end (of the month) was really a lack of sun. It was depressing ... and it was a situation we saw across southern Ontario,” he said.
We head into Winterlude on a high note.
“This week is just perfect, not so cold that people can’t enjoy the activities,” he said.
“The ideal would be to keep morning, noon and night temperatures below freezing, and that is certainly what we see for the next 10 days.”