The areas hit hardest by the 2003 heat wave (red), relative to July averages for 2000, 2001, 2002, and 2004. (NASA)
Many Muscovites wore masks in August 2010 when a heat wave—accompanied by smog and smoke from nearby wildfires—gripped the Russian capital. The city’s mortality rate doubled as the concentration of atmospheric carbon monoxide soared to more than double acceptable safety norms.
2014 U.S. National Climate Assessment maps show projected increases (in degrees Fahrenheit) for the average temperature on the hottest days by late this century (2081–2100) relative to 1986–2005, under scenarios RCP2.6 (left) and RCP8.5 (right). “Hottest days” are defined here as those so hot they occur only once in 20 years, on average. Such days would be about 10–15°F hotter for most U.S. residents under RCP8.5. (U.S. National Climate Assessment/NOAA National Climatic Data Center/Cooperative Institute for Climate and Satellites, North Carolina)
For the contiguous United States, the last 40 years have seen an increasing proportion of daily record highs to record lows, as reflected in data from about 1800 weather stations. (The ratio shown for the 2000s extends from January 2000 to September 2009.) (UCAR)