Be sure to click through to see the map that shows the temperature changes. As you might imagine, the US was mostly much warmer than the recent historical average.
July 2012 was the hottest month on record for the contiguous (lower 48) United States, according to the National Climatic Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA). It turns out that the month was pretty warm globally as well, lining up as the fourth warmest July since modern record-keeping began in 1880.
The map above shows temperature anomalies for July 2012, as analyzed by the NASA Goddard Institute for Space Studies (GISS). That is, the map shows how much warmer or cooler each area was in July 2012 compared with the average for the month from 1951–1980. To build their map, scientists at GISS use publicly available data from 6,300 meteorological stations around the world; ship-based and satellite observations of sea surface temperature; and Antarctic research station measurements. For more explanation of how the analysis works, read World of Change: Global Temperatures.