Central Indiana endures warm, dry fall for 2017

The arrival of December marks the conclusion of meteorological fall and welcomes meteorological winter.

Temperatures remained above average throughout much of the first half of the fall, before cooling to below-normal levels through much of November.

Overall, the fall of 2017 saw average temperatures above normal by 1-3 degrees. Dry conditions that developed in August after the exceptionally wet first half of summer continued through September and October, with many parts of central Indiana running up to two inches below normal on precipitation.

Most of central Indiana saw the first snowflakes of the season in late October, the first time that had happened since 2014. Additional minimal snowfall amounts from a trace up to near an inch occurred in November across northern portions of central Indiana.

The following is a summary of weather conditions experienced in Central Indiana during September, October and November.

Temperatures

The fall of 2017 was tied for the 22nd warmest fall ever at Indianapolis with an average temperature of 57.3 degrees, which is 2.1 degrees above the normal fall average.

September

September 2017 will be remembered for its extremes, as the first half of the month was largely much cooler than normal followed by a flip to much warmer conditions for the second half of the month. Temperatures averaged 1-3 degrees above normal for the month.

The remnants of Hurricanes Harvey and Irma contributed to cooler weather over the Ohio Valley. Once the remnants of Irma departed off to the northeast on the 14th, a transition commenced to a much warmer conditions for the second half of the month. Highs recovered into the 80s beginning on the 15th and would stay at or above 80 degrees through the 27th. Much of central Indiana would experience its hottest temperatures of 2017 during a stretch from Sept. 20-26 where highs were routinely at or above 90.

Indianapolis warmed into the 90s for six consecutive days from Sept. 21-26, including tying record highs on the 22nd, 24th and 26th. The high of 93 on Sept. 22 was not only the warmest temperature officially recorded in Indianapolis for the year, it also became the warmest temperature on a Fall Equinox in recorded history.

October

Warmth dominated the first half of October, with some days even having a summer-like feel to them. High temperatures reached the middle 80s a couple of times during the first week of the month at many locations.

A cold front, and the remnants of Hurricane Nate, brought cooler temperatures for part of the second week of the month. However, warmer air refused to stay away. By Oct. 14, temperatures had returned to the 80s.

For the Indianapolis area, the first 23 days of October averaged the fifth warmest of record and the warmest since 2007. Big changes were on the way though.

A shift in the jet stream allowed a potent cold front to bring much colder air to central Indiana to close out the month. Temperatures reached their coldest levels since spring, with many areas falling below freezing by the morning of the 26th with highs closer to normal for early December.

The last eight days of October averaged the eighth coldest of record for the Indianapolis area and was the coldest since 1988.

November

November started out warm with highs in the 60s across much of the area. Temperatures peaked on Nov. 5 ahead of a strong cold front that moved across central Indiana late in the day. Highs rose into the 70s ahead of thunderstorms, marking the high point for temperatures for the entire month.

Temperatures were cooler behind the front but remained generally near normal into Thanksgiving week with highs in the 40s and 50s.

High temperatures surged to nearly 20 degrees above normal in the 60s on multiple days at the end of November. After a few chilly mornings in the lower and middle 20s on Thanksgiving week, lows warmed into the 30s and even low 40s for the last few days of the month.

Precipitation

Overall 2017 was the 56th driest fall on record at Indianapolis. Total rainfall for Indianapolis this fall was 7.57 inches, which was 2.37 inches below the normal fall rainfall total of 9.94 inches.

The dry spell that began in late July in southwest and west-central Indiana continued into September. Much of this area received less than an inch of rain during September. Moderate drought conditions developed in much of west-central Indiana by Sept. 19.

Highlighting just how dry conditions have gotten in the area, Indianapolis experienced the wettest day of 2017 on July 11, when 3.78 inches of rain fell. From July 12 through the end of September, Indianapolis officially recorded 3.8 inches of rain.

The dry spell that began in the state during late July ended by Oct. 28.

The season’s first frozen precipitation fell in central Indiana during the afternoon of Oct. 27. Ice pellets and snowflakes were reported in much of the area. The last time winter precipitation had fallen in the Indianapolis area during October was on Oct. 31, 2014.

Monthly precipitation for November was near normal to above normal for much of Indiana. Monthly snowfall for November ranged from a trace to an inch in central and northern Indiana.

Winter Outlook

The official outlook for the 2017-18 winter season (December-February) from the Climate Prediction Center, indicates equal chances for near-, above- or below-normal temperatures across central Indiana. At Indianapolis, the average temperature for the winter season is 30.5 degrees.

The outlook also calls for a greater chance of above-normal precipitation. The average precipitation is 8.15 inches with 22 inches of snowfall, according to data prepared by the NWS Indianapolis Climate Team.