The National Oceanic and Atmospheric Administration (NOAA) reports:
The average U.S. temperature in 2017 was 54.6 degrees F (2.6 degrees F above average), making 2017 third warmest year in 123 years of record-keeping, according to scientists from NOAA’s National Centers for Environmental Information. In fact, the five warmest years on record for the U.S. all have occurred since 2006.
2017 was also was the 21st consecutive year that the annual average temperature exceeded the average. For the third consecutive year, every state across the contiguous U.S. and Alaska experienced above-average annual temperatures.