Another US temperature record - for September

Lower 48 States See Second Warmest September On Record

Wunderground,

9 October,2015

September 2015 was the second warmest September on record for the contiguous United States, according to a new NOAA report.

September's mean temperature over the Lower 48 States of 68.54 degrees Fahrenheit was not only 3.68 degrees above the long-term (1901-2000) average, but was second only to 1998 on the list of the warmest Septembers in 120 years of record-keeping.

September 2015 temperature anomalies over the Lower 48 states, relative to the 20th century average. Deeper pink, red contours correspond to areas progressively warmer than average in September 2015. Blue shaded areas indicated areas cooler than average.
(NOAA/NCEI)

Nine states from New England to the Four Corners and Desert Southwest – Maine, Rhode Island, Connecticut, Michigan, Wisconsin, Minnesota, Colorado, New Mexico and Utah – sweated through their record warmest September.

The statewide September warmth record had stood since 1931 in both Michigan and Wisconsin. In Minnesota, that 1931 record was shared with 1897.

Twenty other states had one of their top 10 warmest Septembers in 2015. Six of those 20 states – New Hampshire, Vermont, Massachusetts, New York, New Jersey and Wyoming – had their second warmest September.

September 2015 statewide temperature rankings. Red-shaded states denote those setting a record warm September. Orange-shaded states denote those with a top 10 warmest September in 2015.
(NOAA/NCEI)

According to an analysis from the Southeast Regional Climate Center (SERCC), dozens of cities from New England to the Great Lakes, Plains, Rockies and Desert Southwest had their hottest September on record, including:

• New York City (Central Park)
• Burlington, Vermont
• Portland, Maine
• Sault Ste. Marie, Michigan
• La Crosse, Wisconsin
• Peoria, Illinois
• Fargo, North Dakota
• Denver
• El Paso, Texas
• Las Vegas
• Long Beach, California

West On Pace for Warmest Year

The first nine months of 2015 were the warmest January-September periods on record in California, Nevada, Oregon and Washington.

Eight other states have had one of their top 10 warmest first nine months of any year, including the rest of the Rockies and Desert Southwest states, as well as Florida. Four of those eight states – Montana, Idaho, Utah, and Arizona – narrowly missed their record warmest first nine months of any year.

January-September 2015 statewide temperature rankings. Red-shaded states denote those setting a record warm January-September. Orange-shaded states denote those with a top 10 warmest January-September in 2015.
(NOAA/NCEI)

Perhaps most astounding was California's warmth. For the second year in a row, the Golden State set its record warmest January-September, owing that in part to the long-term drought.

Those two January-September periods each topped the previous record warm first nine months of any year which had stood since 1934 by 1.3 degrees and 1.5 degrees Fahrenheit, respectively. In the realm of statewide average temperatures, this is akin to smashing a track and field or swimming record by a half-second or more.

California January-September mean temperatures since 1895. The red box highlights 2014 and 2015, each smashing the previous record warmest such period in California from 1934.
(NOAA/NCEI)

Some cities that set or tied their record warmest January-September periods in 2015, according to the SERCC, including Seattle, Portland, Oregon, Reno, Nevada, Las Vegas, Salt Lake City, Phoenix, and Long Beach, California.

For the Lower 48 states as a whole, the first nine months of 2015 were the eighth warmest such period dating to 1895.

Despite that, five states from the Ohio Valley to the interior Northeast remained cooler than average from January through September. 

Bangor, Maine, despite its fourth warmest September, still had a top 10 coolest year-to-date through the end of September, according to the SERCC.

Wet and Dry Highlights

It's no surprise the first nine months of 2015 were among the top 10 driest in both California (fourth driest) and Oregon (fifth driest). Connecticut (seventh driest) also made that top 10 list.

Despite a burgeoning late summer/early fall drought, January through September was among the top 10 wettest such periods in both Oklahoma and Texas, largely due to the epic rainfall in May and June.