A long last, the atmosphere is handing Chicago a three-day period of pleasantly sunny, cool and dry weather in what has otherwise been a cloudy, chilly and record-wet year. Year-to-date precipitation stands at 24.17 inches, the most ever for that period in 143 years of Chicago weather history -- and in remarkable contrast to the withering drought that prevailed at this time one year ago. Year-to-date precipitation then was a meager 12.64 inches. The weather doesn't play "catch up," but sometimes it seems as if it does.

Thundershowers moved across the Chicago area Monday afternoon, producing brief but heavy downpours. Selected rainfall totals:

0.30"  Clarendon Hills

0.24"  Downers Grove

0.20"  Hinsdale, Western Springs  

0.15"  Midway Airport (courtesy of Frank Wachowski)

0.02"  O'Hare International Airport

Canadian air that arrived late Monday afternoon has established residence across the Midwest and, in fact, is forecast to push to the Gulf states by Thursday. Chicago area locations that flirted with, and even exceeded, 90 degrees on Monday will struggle to get out of the 60s Tuesday. In yet another weather reversal, heat and humidity return by the weekend -- and that will bring the next threat for rain.

Until then, three rain-free days (Tuesday, Wednesday, Thursday) are expected, and that will be Chicago's longest "dry spell" in four weeks (since a 6-day dry period May 11-16).

Monday will be another warm day with afternoon temperatures heading well into the 80s, but cooler air of Canadian origin is headed toward the city. A cold front that marks the leading edge of the cooler air arrives Monday evening, accompanied by hit-and-miss showers and thunderstorms. Cold frontal boundaries usually serve to trigger considerable thunderstorm activity, but atmospheric conditions this time are not especially favorable for thunderstorm development. Only scattered storms are expected (though some could be vigorous) and it's possible that rain will spare as much as 50 percent of the metropolitan area. Once in place by Tuesday morning, Canadian air -- relatively cool and quite dry -- will keep area temperatures in the 70s through mid-week. Following that, a strong warming trend begins Thursday, culminating in 90 degrees by Saturday.