Wash the thermometer in soap and rinse with cool, clean water before and after you use it. Do not use hot water because the thermometer may break. After washing, it is best to soak the thermometer in alcohol for 20 minutes. You can use ethyl, isopropyl, or medical alcohol (ethanol).
1 In 2015, the average temperature across global land and ocean surfaces was 1.62Â°F (0.90Â°C) above the twentieth-century averageâthe hottest year in the 136-year record.  Since 1976, every year has been warrmer than the long-term average.
1 The average annual temperature is 28.1 degrees Celsius (82.6 degrees Fahrenheit). 2  See the temperatures page for a monthly breakdown and the fixed scale graph. 3  Average monthly temperatures vary by 3.5 Â°C (6.3Â°F).