Quick Facts:

	Ave	10Y	Low (Year)	High (Year)
HLA	50.53	50.19	46.69 (2011)	56.31 (2012)
Highs	79.62	80.10	72°F (2018)	85°F (2013)
Lows	23.15	21.40	12°F (2018)	36°F (2020)
Precip	2.29”	2.21”	0.07” (2018)	4.52” (2010)

 

 

January Temperatures

January’s 13-year temperature average is 50.53°F, more than three degrees cooler than either December or February, making January the coldest month of the year (on average). It is not necessarily the coldest month of each year; February was colder twice (2010 and 2021) and December was colder three times (2013, 2017, 2020). (And, a few times, a January has been warmer than the immediately preceding December.)

January 2012 was the warmest January on record for this region, with a high-low average of 56.31°F (second place is a tie between 2017 and 2020, at 54.89°F). I don’t know when the coldest one was, but the coldest recent January was 2011, with an HLA of 46.69°F.

According to a variety of sources I searched, the coldest temperature ever recorded in January was 11°F, on Jan. 2, 1979, while the warmest temperature January has ever seen was 87°F, on both Jan. 3, 2006, and Jan. 19, 2000. During my 13-year record-keeping period (2010-22), the coldest January day was Jan. 17, 2018, when we saw 12°F, and the warmest was 85°F, on Jan. 24, 2013. Eight daily record lows were during the past 13 years, compared to 13 daily record highs during the same period.

January averages about six freezing days per year — days in which the low is 32°F or cooler — more than any other month. To my knowledge, 2020 was the first time in history in which January saw zero freezing days; the low for the entire months was 36°F. We seem to get fewer freezing days each year. The three year period of 2019-2021 saw fewer freezing days than any other two-year period.

 

 

Precipitation

Rainfall in January varies from 4.52 inches (2010) to 0.07 inches (2018), typically flipping back and forth from very wet to very dry each year, though 2019-2021 saw three consecutive above-average years. The 10-year average, 2010-19, is 2.22” of precipitation.

January averages 7.4 days per month that see precipitation, with a maximum of 13 days (2020) and a minimum of four (2014).

Trends And Patterns

January’s tempertures rise and fall in a regular pattern (two years above average and two years below average), as does the rainfall, but the two patterns do not seem related to each other.

On neither rainfall nor temperature is January a good predictor for the rest of the year. For example, January’s HLA dropped by more than a degree from 2010 to 2011, but the yearly HLA rose more than a degree between those two years. Similar observations emerge on the rainfall charts; sometimes January gets increased rainfall but the year is relatively dry (2013); other times January is dry but the year is wet (2016).

I did notice that the uptick in temperature in 2020 was only three years after the previous peak, while the gap before that was five years long. This might mean nothing in the long run, or it could mean that our warming periods are getting closer together.

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