They say variety is the spice of life, and that certainly holds true for the weather. But this mid-summer month of July is often one of little variety across the country.

Hot, humid, stagnant air masses gather for days and weeks at a time. These are the "dog days" of summer, so named because thousands of years ago the Romans noted the bright star Sirius was in the same position in the sky as the Sun.

Sirius is in the constellation Canis Major (the big dog), and they reasoned that its combined heat along with our Sun made for hot summer days ... dog days. We now know that the output of heat we feel from Sirius is about one ten-millionth of the Sun's output, but the dog day term remains.

Forget the dogs: July weather watchers should keep an eye out for the 15th of the month. That is St. Swithin's Day. He was the bishop of Winchester, England, and when they attempted to rebury him in a more honored spot 100 years after his death, the proceedings were delayed for 40 days due to torrential rain. That was in 862 A.D. Today the weather lore states that 40 days of rain will follow if it rains on July 15.

Here in the northern third of the United States we can get some variety in the dog days, unlike states farther south. Our stagnant, hazy weather is usually due to the jet stream moving well north of us and taking the main weather systems north into Canada. A dome of slow-moving high pressure settles in at the Earth's surface as well as aloft, acting like a rock in a stream. The high pressure dome blocks incoming fronts that would normally plow through and bring in a refreshing air mass change. But that jet stream can dip down south of the U.S.-Canada border and allow cold fronts to bust into the Great Lakes. Those fronts help touch off severe thunderstorms, but they also drop the dew points and make it much more comfortable.

Another reason we see more variety of summer weather here is Lake Michigan. Breezes off the lake offer instant relief. People in Moline, Cedar Rapids and Minneapolis don't get that benefit.

July 4 in Milwaukee is a significant weather day because it marks the anniversary of our highest dew point on record, a whopping 82 degrees in 1977. We matched that mark again on July 30, 1999. The 13th of this month is noted for the hottest temperature on record in Wisconsin: 114 degrees at the Wisconsin Dells in 1936. (Too bad there weren't water parks around at that time!)

This month also lays claim to the warmest low temperature on record in Milwaukee: 84 degrees on July 14, 1995. The high later that day was a record 102 degrees.

So sit back, relax, and enjoy the many faces of July weather in Milwaukee. It's rarely boring and often exciting. And they can't always say that in Moline.

Watch Vince Condella on Fox 6 Sunday through Thursday at 5, 6 , 9 and 10 p.m. You can see the FOX 6 weather forecast around the clock at www.fox6milwaukee.com