August And January Trends
The white dots on the graph above show the HLA (high-low average) for each month since January 2010, while the blue and red lines show trends for January and August, respectively.
(Copyright © 2017 by Wil C. Fry. Some rights reserved.)
While the early months of this year were the warmest of all time for this area, that trend has flattened in summer, especially with August.
August 2017 was the coolest August since we moved here — I have eight years of records. I can’t compare it to previous Augusts in history, because that information simply isn’t available from official weather agencies. I show an HLA (high-low average) of 85.21°F for the month — this is the average of all 31 daily highs and lows for the month — which is a full eight degrees cooler than our hottest August (2011) of all time. It’s also cooler than all but one of our Julys, and cooler than three of our Junes.
There were only seven 100-degree days, the fewest in the past eight years. It’s also the first time since we moved here that August saw fewer 100-degree days than did July.
Twenty-five days hit 90°F or higher, which is a tie for the fewest among the past eight Augusts, and it’s the third year in a row that August lost to July. In fact, July now averages more 90-degree days than August.
101°F was the high for the month, the lowest August high since we moved here, and only the second time that August didn’t beat July’s high.
69°F was our low, which was unremarkable. August’s average low is now lower than July’s.
We received 4.38 inches of rainfall in August, the second-rainiest August since moving here (August 2016 is the record holder). Both August 2017 (4.38″) and August 2016 (8.01″) saw more rainfall than all the other Augusts combined (3.89″). August now averages more rain than July.
Seven days saw precipitation, which is the second-most for August. August’s average for rainy days is now higher than July and October.
Earlier this year, due to the surprising warmth, I began to suspect 2017 would surpass 2012 as our hottest year of all time. It is still possible — 2012’s summer wasn’t overly remarkable for its heat; the record came from the winter, fall, and spring months. But this surprisingly cool August puts a serious dent in 2017’s chances.
Four of 2012’s monthly HLA records still stand (January, April, May, and December). In order for 2017 to overtake 2012 at this point, we need to be above average temperature for the next four months, which is easily possible. September varies less than any other month, October has been on a strong warming trend the past eight years, November could go either way, and December looks due for another warm one too.
Rainwise, we have already received more rain than two entire years (2011 and 2014), and if current trends continue, we’ll beat all but 2015. More than any of the past seven years, 2017 has seen the rain spread evenly throughout most months, with few long dry spells.