2018 European heatwave, temperature anomaly map. This temperature anomaly map is based on data from Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite. It shows land surface temperatures from July 1-15, 2018, compared to the 2000-2015 average for the same two-week period. Red colors depict areas that were hotter than average; blues were colder than average. This heatwave was part of a larger heatwave affecting most of the northern hemisphere, caused by the jet stream being further north than usual. One of the consequences was an increase in wildfires in Sweden and neighbouring countries in Scandinavia.