Brian Palmer explained how the National Oceanic and Atmospheric Administration (NOAA) measures the average temperature across the United States:

• NOAA has 1,218 thermometers, most of which are automated and transmit data wirelessly.
• The average temperature of the country is the average of the high and low for the day, averaged across all 1,218 measuring stations.
• A lot of these weather stations are located around airports because the surrounding areas are sparsely populated leading to more accurate readings.
• The United States has the best data. Temperature worldwide is measured by NOAA through 7,280 thermometers. 32% of the official land-based ones are in the United States – even though it only has 6% of global land mass.

To read more including the statistical tools that NOAA uses to finesse its data, the thermometers used by NOAA, why the thermometers were moved off of urban rooftops in the 60s, how it ensures its data is consistent through the years, and how NOAA measures global temperature, click here.

Source: Slate