Month-long periods of extreme weather are associated with amplified atmospheric planetary waves - high-altitude winds that meander around the globe - occurring in the mid-latitudes, reports a study published online this week in Nature Climate Change.

James Screen and Ian Simmonds identified mid-latitude land temperature and precipitation extremes in observational datasets. Comparing the extremes with planetary-wave amplitude anomalies across seven mid-latitude study regions allows differences in impacts to be determined. The authors identified the type of extreme expected in different geographical regions, with an increased probability of heatwaves in western North America and central Asia, cold periods in eastern North America, droughts in central North America, Europe and central Asia, and wet spells in western Asia.