The winter of the Boise deep freeze continued Tuesday morning, when the National Weather Service recorded a low temperature of -3 at the Airport — and Idaho’s capital city seems to be the warmest place in the Treasure Valley.

The National Weather Service reported lows of -9 in Ontario, -6 in Mountain Home, and -4 in Nampa and Caldwell Tuesday morning.

The -3 also means the Boise area dipped into subzero temperatures for the fourth day in row, with recorded lows of -3, -1 and -1 since Saturday.

The estimated high for the Boise area Tuesday is 21 degrees. We also have an orange air quality alert for the fourth day in a row.

So when will all this subzero temperature and frozen pollution stuff end? Not until Wednesday night at the earliest, and it might not even be that much of a change until the weekend, said Les Colin, a meteorologist at the National Weather Service.

It might stay above 0 Wednesday morning as some clouds are expected to move into the Treasure Valley by Tuesday afternoon, but overnight temperatures will likely remain in the single digits, Colin said.

The weather system officials hoped would move through the Treasure Valley Wednesday and knock out the inversion that has been trapping cold temperatures and pollution by the ground doesn’t look strong enough for that to happen. Stiffer winds might mix it up the air a little bit starting Wednesday but a major change is more likely to occur Saturday, Colin said.

Still, it should be a little bit warmer. High temperatures may get into the low 30s beginning Wednesday but overnight lows could still flirt with single digits until the weekend

Treasure Valleyans have now endured three solid weeks of frigid temperatures. All but two days in January have been below normal — and not just a little. We're talking average daily temperatures that have been 10 to 24 degrees below normal.

For example, the high temperature in Boise on Monday was 17 degrees. The high on Jan. 21, 2012 was 49 degrees. The average high temperature for Jan. 21 is 38 degrees.

The city of Boise is on track to record the fifth coldest January on record since 1865, according to the National Weather Service. The average temperature for the month (so far) is 15.7 degrees, which is 14.8 degrees below normal.

The Department of Environmental Quality issued an orange air quality alert for Tuesday. That means those in sensitive groups, including children, the elderly and those with lung conditions, are advised to limit time outdoors. All open outdoor burning is prohibited throughout Ada and Canyon counties.