Remember the summer of smoke? Now it’s the winter of ice in Boise and surrounding areas, with some slightly lousy air quality thrown in as a bonus.

The low temperature at the Boise Airport on Friday morning was 1, which was recorded at 6 a.m. The high for Friday was a measly 17 degrees, according to the National Weather Service.

Just how cold has it been?

Since the beginning of January, the overnight lows have been in the single digits 11 times — a trend that will continue until Monday, when the overnight low is predicted to reach 10. The projected highs for the weekend are in the low to mid-20s, and it’s more of the same for Monday and Tuesday.

Cold air — and dirty, too

You can also add a yellow (moderate) air quality alert for the Treasure Valley to the mix, thanks to a stubborn inversion that has kept cold air — and particulate matter, car emissions and other pollution — trapped near the Valley floor the past week or so.

The Department of Environmental Quality forecast an Air Quality Index of 98 for Saturday (that’s two points away from an orange alert, meaning unhealthy for sensitive groups). Officials advise people to postpone strenuous activities outside and limit driving if possible.

When will we get a thaw?

The National Weather Service is saying that might happen on Wednesday, when a weather system with slightly warmer air is expected to move through the region. Temperatures could hit 38 degrees by midweek, meteorologist Valerie Mills said. The overnight low might actually be above 20.

Is this unusual?

For those of you complaining about the cold, you are apparently totally justified, even though it’s winter. It has been unusually frigid, and the numbers prove it.

“Every day this month except for two, we have been at least 10 degrees colder than normal,” National Weather Service meteorologist Les Colin said Friday morning.

You want more proof? The temperature has been above freezing in Boise just three times since Dec. 28 — on Jan. 8, 9, and 10. Only on one of those days — Jan. 9, when the average temperature was 33 degrees — did it stay above freezing for an entire 24-hour period.

Any more snow?

Probably not the next few days, according to forecasts. There isn’t a chance of snow greater than 20 percent until next weekend.

Patrick Orr: 377-6219, Twitter: @IDS_Orr