They are reported in 29 countries for the period May - August.
Nearly 400 absolute temperature records were broken during the summer in the Northern Hemisphere. This shows an analysis of measured values by the California-based Berkeley Climate Institute.
The records were improved in 29 countries from May to August. One third of the highest temperatures ever measured were reported in Germany, followed by France and the Netherlands.
The data include measurements from weather stations in the Northern Hemisphere that have at least 40 years of observations. Some have been reporting temperatures for more than 150 years and have also measured all-time highs.