The Lower 48 had its warmest autumn on record for the second year in a row, with an average temperature for the September-through-November period of 57.6 degrees Fahrenheit, which is 4.1 degrees above the 20th century average, the National Oceanic and Atmospheric Administration said in its latest "State of the Climate" report. The previous record, from 2015, was 56.8 degrees F.
Autumn temperatures were above average across nearly the entire country, with the warmest anomalies observed across the northern tier states. Colorado, Iowa, Kansas, Michigan, Minnesota, New Mexico, Texas and Wisconsin each had a record warm autumn, while another 27 states each had either its second or third warmest autumn on record.
Both the average daytime and nighttime temperatures across the contiguous U.S. in autumn were the warmest in the 122-year period of record.
Autumn was capped by the second warmest November on record for the Lower 48, which had an average temperature of 48.0 degrees F, or 6.3 degrees above average. The warmest November on record occurred in 1999, when the average monthly temperature reached 48.1 degrees F.
"Every state in the Lower 48 experienced an average temperature that was at least above average," the NOAA said. Record warmth was observed for Idaho, North Dakota and Washington in November, while near-record warmth was seen in the western half of the country, where 15 states each had their second or third warmest November.
"Since 1970, the average November temperature for the contiguous U.S. has been warming at a rate of 6.6 [degrees] F per century," the NOAA said. Only January is reportedly warming at a faster rate, at 10.5 degrees F per century.
Based on the NOAA's Residential Energy Demand Temperature Index, the Lower 48 November temperature-related energy demand was 6.7, the third lowest value on record, reflecting diminished heating requirements due to above-normal temperatures.
For the year-to-date period, the average temperature in the contiguous U.S. was 56.9 degrees F, the second warmest in the period of record. The warmest January-through-November period on record was seen in 2012 when the temperature for the 11-month start to the year averaged 57.0 degrees F.
Louisiana had its sixth warmest January-through-November period on record, the only state to have a year-to-date temperature outside the top five warmest. Georgia, Montana, North Carolina, North Dakota, South Carolina and Virginia each had a record warm 11-month start to the year.