Julia Poska | October 2, 2019
Some areas of the United States entered October in summer-like heat while others faced frosty cold and intense rain.
Dry heat is scorching the south and eastern parts of of the country. More than a dozen cities — including Cleveland, New Orleans, Nashville and Indianapolis — broke high temperature records for the whole month of October. The Weather Channel forecasts that records may continue to break through Thursday.
Meanwhile, states like Montana, Idaho and Wyoming felt unseasonable cold, with temperatures in 38 degrees Fahrenheit in Boise, Idaho. These temperatures follow a frosty weekend in the region, with record-breaking cold and snowfall.
The Weather Channel attributes the temperature extremes to an especially dramatic curve in the polar jet stream — a fast-moving, high-altitude band of wind that impacts weather throughout the hemisphere. Right now, the jet stream dips abnormally southward in the Western U.S. and soars abnormally northward in the east for this time of year.
Storms and floods along the stream’s path (where, the hot/dry and cool/wet air masses meet) are threatening parts of Minnesota, Iowa, Nebraska, Kansas, Colorado and New Mexico.
Studies say climate change alters the jet stream, intensifying weather phenomena like the “polar vortex,” though it is difficult to determine whether greenhouse gasses are playing a role in this week’s weather patterns.