When scientists in the 1960s - 70s compiled data to build their global average temperature series they used state averages of monthly mean temperatures from weather stations around the world. (skepticalscience.com)
Observed change of monthly mean temperature for Northern Norway since year 1900, relative to the 1901 - 2000 mean. (folk.uib.no)
The warm anomalies in June lasted throughout the entire month (increases in monthly mean temperature of up to 6 to 7 °C), but July was only slightly warmer than on average (+1 to +3 °C), and the highest anomalies were reached between 1st and 13th August (+7 °C)(Fink et al., 2004). (ipcc.ch)