There is a meteorologist's rule of thumb that says a cool autumn often is followed by a colder than normal winter.
With that in mind, be aware that Arctic cold waves have caused unusually chilly weather of late in parts of Europe, North America and Asia.As a result, Moscow had its earliest snowfall in 16 years and Stockholm, Sweden, has been blanketed by its heaviest October snow storm since 1925. In North America, a 26 below zero temperature already has been recorded in northern Canada and 11 below zero in Fairbanks, Alaska.
Meteorologists and climatologists say the eruption of Mt. Pinatubo in the Philippines in June 1991 has caused the Northern Hemisphere's temperatures to decline one or two degrees. That means the volcanic eruption is only partially responsible for this autumn's unseasonably cold weather.
Weather forecasters simply don't know what the other reasons are for the chill, weather service climatologist Rich Tinker said.
The hemisphere's coldest Arctic outbreaks have been in Scandinavia and western North America. October temperatures in Sweden, Finland, northern Russia and western Siberia were 10 to 15 degrees below normal and whistling winds in Siberia caused 60 below zero wind chills.
"There's a place in Finland called Sodankyla whose October temperature averaged 21 degrees below normal," Tinker said. "The town already has had 16 below."
In western North America, unusually cold weather has gripped parts of Alaska, the Yukon, British Columbia and Alberta since early September and chunks of this atmospheric iceberg have broken off and chilled Montana, the Dakotas, Wyoming, Nebraska and parts of nearby states.
Temperatures in the western United States and Canada have averaged 8 degrees to 15 degrees below normal, but some areas have experienced wild temperature swings. Edmonton, Alberta, for example, had an 83 degree reading on Sept. 29, then plummeted to 12 degrees on Oct. 16.
Pockets of coldness also have chilled Scotland, Ireland and Northern England and the Netherlands, Germany and Poland.
Warmer than normal autumn temperatures have occurred in several areas of the Northern Hemisphere - notably California, Arizona and Nevada, most of the Mediterranean basin and a swath of Siberia from Vladivostok to Lake Baikal.
In case you forgot, last autumn most of the country had seasonal temperatures and they were followed by a marvelously warm winter. That clearly isn't what's happening this year.