Kevin Myatt is The Roanoke Times' weather columnist.

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Autumn has been tardy the past two years.

But by Thursday morning, we should know that it's running right on time this year, or actually, even a little ahead of the bell.

The season's first real Canadian cold front moved through the area on Tuesday, and high pressure from the north brought in air originating in the tundra region. With high pressure settling overhead tonight, leading to a clear, calm night, low temperatures on Thursday morning will likely range from the 30s in some of the deeper mountain valleys to our west to no higher than the mid-40s even in more urban areas like Roanoke.

For the record, May 24 was the last day we saw a low below 50 in Roanoke, when it dipped to 44. In 2005, we didn't see a low below 50 until the last day of September, when it finally dropped to 43.

September so far has been much different than the same month has been in the last two years. Through Monday, Roanoke's average temperature for the month is running 2.6 degrees below normal for the month. September 2005 was 3¹₂ degrees above normal, while September 2004 was more than a degree above normal.

September 2005 was dominated by a warm, dry high-pressure system. We only got 0.23 inch of rain in September a year ago, as the high-pressure system served to deflect cold fronts away from us and also the season's many hurricanes.

September 2004, by contrast, was different in that we were repeatedly soaked by hurricanes moving inland. Warm, moist tropical air settled in for many weeks during that fall.

We've had cold fronts moving through at pretty close to regular intervals in this September so far. As a result, we've gotten periodic rain and occasional cool-downs. This will be by far the coolest front so far, as air from the northern reaches of Canada works its way down for the first time in four months.

This won't be a long cool snap; temperatures are expected to rebound into the 70s for highs and 50s to low 60s for lows by the weekend. But there is yet another cold front on the way late in the weekend or early next week. The new front may bring some showers and thunderstorms with it as it sweeps into some humidity from the Gulf of Mexico.

If this pattern of periodic cold fronts keeps up, we may actually see an October that acts like October with cool, crisp days and colorful leaves.

It's nice to see a season arrive on time for once.