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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Second-Warmest Year in U.S. Weather History, and Among the Wettest
Only 2012 ranks ahead of 2016 for average temperature across the 48 contiguous states, said NOAA’s National Centers for Environmental Information on Monday in its yearly U.S. climate report. The second-place showing follows a third-place ranking in 2015 (see Figure 1), which means that the last five years (2012 - 2016) have produced the three warmest years in U.S. records extending back to 1895. This national-scale warmth is a reflection of global-scale trends consistent with a climate being warmed by human-produced greenhouse gases. It’s virtually certain that 2016 will be certified this month as the warmest year on record globally, which would make it the third such record-setter in a row.
The average 48-state reading of 54.91°F in 2016 was 2.89°F ahead of the 20th-century average and 0.37°F shy of the 2012 record. Geographically, the nation’s warmth in 2016 was astoundingly uniform, with every contiguous U.S. state having at least its seventh warmest year (see Figure 2). Georgia had its warmest year on record, as did Alaska, which isn’t part of the contiguous U.S. database.
Figure 1. Year-by-year average temperature for the 48 contiguous U.S. states from 1895 to 2016. The three warmest years have all occurred since 2012. The current U.S. climate is roughly 1.5°F warmer than it was a century ago, with much of that warming observed since the 1980s. Image credit: NOAA/NCEI.
Figure 2. Statewide rankings for average temperature in 2016 as compared to each calendar year since 1895. Darker shades of orange indicate higher rankings for warmth, with 1 denoting the coldest year on record and 122 the warmest. Image credit: NOAA/NCEI.
Figure 3. Month-by-month rankings for U.S. temperature and precipitation in 2016, including the average temperature, daily maximum and minimum temperature (each calculated locally before being averaged nationally), and precipitation. Higher numbers denote a warmer or wetter placement among the 122 years in the NOAA database, which extends back to 1895. Data credit: NOAA/NCEI.
Warmest nights on record
Sultry summer nights--and mild winter nights--did more than their share to put 2016 near the top of the U.S. temperature heap. Averaged across the nation and year, the daily minimum temperature was the warmest in U.S. history, at 3.09°F above the long-term mean (beating out 2012). The average daily maximum temperature came in at 2.69°F above the 20th-century average, placing third behind 2012 and 1934. Relative to average, lows were warmer than highs for every month in 2016 except February and March, as shown in Figure 3.
The year’s U.S. warmth was well distributed across the calendar, with two noteworthy exceptions evident in Figure 3 above: May and December.
Record highs outdid record lows by an unprecedented ratio
What’s not obvious in the maps and figures above is how seldom U.S. towns and cities set or tied daily record lows in 2016, thanks in large part to the mild nights noted above. The preliminary total of daily record lows for the year was 5188--barely half of the total recorded in any other year since 30-year climatologies became established in the 1920s, according to independent meteorologist Guy Walton, who has compiled and tracked NOAA records data for more than a decade. Meanwhile, there were 29,729 daily record highs, a large but not unusual number for recent years. Juxtaposed, the ratio of daily highs to daily lows was around 5.7 to 1, the largest for any year in the post-1920s database, according to Walton. Overall for the 2010s (defined as 2010 - 2016), we’ve seen more than double the number of daily record highs versus lows, with the ratio of 2.1 to 1 just above the 1.9-to-1 ratio observed in the 2000s.
A wet year overall, but with plenty of variability
Wild spatial and temporal swings were the order of the year in 2016 when it comes to precipitation. Averaged by month, June was the 14th driest on record for the contiguous U.S., while August was the 2nd wettest, as shown in Figure 3. The tendency toward drought east of the Mississippi, and the very moist conditions that prevailed in the upper Midwest (as well as flood-hammered Louisiana), is evident in the state-by-state precipitation map (Figure 5 below). The year as a whole was the 24th wettest on record. Three states had a top-ten driest year--Connecticut, Georgia, and Massachusetts--while Michigan, Minnesota, North Dakota, Wisconsin saw top-ten wet years.
Averaged linearly and nationally, the contiguous U.S. has seen annual precipitation climb from about 29” in the 1890s to about 31” in the 2010s. Of course, that overall rise masks the hugely important swings observed from region to region and year to year.
Figure 4. Year-by-year ranking of average precipitation for the 48 contiguous U.S. states from 1895 to 2016. Image credit: NOAA/NCEI.
Figure 5. Statewide rankings for average precipitation in 2016, as compared to each year since 1895. Darker shades of green indicate higher rankings for moisture, with 1 denoting the driest year on record and 122 the wettest. Image credit: NOAA/NCEI.
A less-crazy December
The parade of midlatitude storms marching across the U.S. in December, a feature characteristic of La Niña winters, led to a fairly unremarkable monthly temperature outcome. It was the 54th coldest and 34th wettest out of the 122 Decembers on record. The La Niña tendency toward cooler-than-average readings toward the northwest and warmer-than-average readings toward the southeast is evident in Figure 6. Florida was the only state with a top-ten temperature result, as it sweated its way through the fourth warmest December on record. Five states--Minnesota, Nevada, North Dakota, South Dakota, and Wyoming--saw a top-ten wettest December (see Figure 7). Moisture has been plentiful across the West apart from the Northern Rockies, and the widespread snowpack now building up (see Figure 8) will be much appreciated by skiers and boarders this winter and by farmers and ranchers next summer.
Jeff Masters and I will have more next week on the natural disasters of 2016, both national and global, as well as how 2016 stacked up in terms of global temperature. We’ll be back with our next post by Wednesday afternoon.
Bob Henson
Figure 6. Statewide rankings for average temperature during December 2016, as compared to each December since 1895. Darker shades of orange indicate higher rankings for warmth, with 1 denoting the coldest December on record and 122 the warmest. Image credit: NOAA/NCEI.
Figure 7. Statewide rankings for average precipitation during December 2016, as compared to each December since 1895. Darker shades of green indicate higher rankings for moisture, with 1 denoting the driest December on record and 122 the wettest. Image credit: NOAA/NCEI.
Figure 8. The amount of water held in snowpack as of January 10, 2017, relative to the average for this date for the period 1981-2010. Image credit: USDA/NRCS and National Water and Climate Center.
The average 48-state reading of 54.91°F in 2016 was 2.89°F ahead of the 20th-century average and 0.37°F shy of the 2012 record. Geographically, the nation’s warmth in 2016 was astoundingly uniform, with every contiguous U.S. state having at least its seventh warmest year (see Figure 2). Georgia had its warmest year on record, as did Alaska, which isn’t part of the contiguous U.S. database.
Figure 1. Year-by-year average temperature for the 48 contiguous U.S. states from 1895 to 2016. The three warmest years have all occurred since 2012. The current U.S. climate is roughly 1.5°F warmer than it was a century ago, with much of that warming observed since the 1980s. Image credit: NOAA/NCEI.
Figure 2. Statewide rankings for average temperature in 2016 as compared to each calendar year since 1895. Darker shades of orange indicate higher rankings for warmth, with 1 denoting the coldest year on record and 122 the warmest. Image credit: NOAA/NCEI.
Figure 3. Month-by-month rankings for U.S. temperature and precipitation in 2016, including the average temperature, daily maximum and minimum temperature (each calculated locally before being averaged nationally), and precipitation. Higher numbers denote a warmer or wetter placement among the 122 years in the NOAA database, which extends back to 1895. Data credit: NOAA/NCEI.
Warmest nights on record
Sultry summer nights--and mild winter nights--did more than their share to put 2016 near the top of the U.S. temperature heap. Averaged across the nation and year, the daily minimum temperature was the warmest in U.S. history, at 3.09°F above the long-term mean (beating out 2012). The average daily maximum temperature came in at 2.69°F above the 20th-century average, placing third behind 2012 and 1934. Relative to average, lows were warmer than highs for every month in 2016 except February and March, as shown in Figure 3.
The year’s U.S. warmth was well distributed across the calendar, with two noteworthy exceptions evident in Figure 3 above: May and December.
Record highs outdid record lows by an unprecedented ratio
What’s not obvious in the maps and figures above is how seldom U.S. towns and cities set or tied daily record lows in 2016, thanks in large part to the mild nights noted above. The preliminary total of daily record lows for the year was 5188--barely half of the total recorded in any other year since 30-year climatologies became established in the 1920s, according to independent meteorologist Guy Walton, who has compiled and tracked NOAA records data for more than a decade. Meanwhile, there were 29,729 daily record highs, a large but not unusual number for recent years. Juxtaposed, the ratio of daily highs to daily lows was around 5.7 to 1, the largest for any year in the post-1920s database, according to Walton. Overall for the 2010s (defined as 2010 - 2016), we’ve seen more than double the number of daily record highs versus lows, with the ratio of 2.1 to 1 just above the 1.9-to-1 ratio observed in the 2000s.
A wet year overall, but with plenty of variability
Wild spatial and temporal swings were the order of the year in 2016 when it comes to precipitation. Averaged by month, June was the 14th driest on record for the contiguous U.S., while August was the 2nd wettest, as shown in Figure 3. The tendency toward drought east of the Mississippi, and the very moist conditions that prevailed in the upper Midwest (as well as flood-hammered Louisiana), is evident in the state-by-state precipitation map (Figure 5 below). The year as a whole was the 24th wettest on record. Three states had a top-ten driest year--Connecticut, Georgia, and Massachusetts--while Michigan, Minnesota, North Dakota, Wisconsin saw top-ten wet years.
Averaged linearly and nationally, the contiguous U.S. has seen annual precipitation climb from about 29” in the 1890s to about 31” in the 2010s. Of course, that overall rise masks the hugely important swings observed from region to region and year to year.
Figure 4. Year-by-year ranking of average precipitation for the 48 contiguous U.S. states from 1895 to 2016. Image credit: NOAA/NCEI.
Figure 5. Statewide rankings for average precipitation in 2016, as compared to each year since 1895. Darker shades of green indicate higher rankings for moisture, with 1 denoting the driest year on record and 122 the wettest. Image credit: NOAA/NCEI.
A less-crazy December
The parade of midlatitude storms marching across the U.S. in December, a feature characteristic of La Niña winters, led to a fairly unremarkable monthly temperature outcome. It was the 54th coldest and 34th wettest out of the 122 Decembers on record. The La Niña tendency toward cooler-than-average readings toward the northwest and warmer-than-average readings toward the southeast is evident in Figure 6. Florida was the only state with a top-ten temperature result, as it sweated its way through the fourth warmest December on record. Five states--Minnesota, Nevada, North Dakota, South Dakota, and Wyoming--saw a top-ten wettest December (see Figure 7). Moisture has been plentiful across the West apart from the Northern Rockies, and the widespread snowpack now building up (see Figure 8) will be much appreciated by skiers and boarders this winter and by farmers and ranchers next summer.
Jeff Masters and I will have more next week on the natural disasters of 2016, both national and global, as well as how 2016 stacked up in terms of global temperature. We’ll be back with our next post by Wednesday afternoon.
Bob Henson
Figure 6. Statewide rankings for average temperature during December 2016, as compared to each December since 1895. Darker shades of orange indicate higher rankings for warmth, with 1 denoting the coldest December on record and 122 the warmest. Image credit: NOAA/NCEI.
Figure 7. Statewide rankings for average precipitation during December 2016, as compared to each December since 1895. Darker shades of green indicate higher rankings for moisture, with 1 denoting the driest December on record and 122 the wettest. Image credit: NOAA/NCEI.
Figure 8. The amount of water held in snowpack as of January 10, 2017, relative to the average for this date for the period 1981-2010. Image credit: USDA/NRCS and National Water and Climate Center.
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.