2010-2018 HLA (August & January)
August is typically the hottest month each year, though that was not the case in 2016 or 2017. January averages as our coldest month, though it's not the case every year -- in 2010, February was cooler, and three times January has been warmer than the December that preceded it.
(Based on the 2010-16 lines, and how January seemed to follow August's up-down path, I predicted that Jan. 2017 would be colder than average, but I was wrong. The following January, however, was very cold.)
* Monthly HLA (high-low average) for Killeen, Texas, based on my own records, from 2010 through January 2018.
I came up with "HLA" as a way to compare days or months from different years. Sometimes the high would be the same, but the low would be different, or vice versa. The monthly HLAs in this graph are averaged from the daily HLAs.
These temperatures aren't official. The official temperatures for Killeen come from the airport, outside the city to the southwest, where almost no one lives, works, or shops. These temperatures are from my house.