RodneyS

No, Topper is correct. The most memorable thing about the 1997-98 El Nino was a run of eight straight 60+ readings at DCA between January 2-9, 1998. However, the maximum was only 69 on January 8th. In fact, we did not reach 80 until March 27th of that year, when the maximum was 81.

Today's high of 77 at Dulles was the warmest ever for this early in the year. At DCA, on the other hand, today's high of 78 set a new record for today, but came up short of the 79 recorded on both January 26, 1950 and February 17, 1976.

Yesterday and today marked the first time since April 29-30, 2014 that DCA recorded consecutive days with at least one inch of precipitation. Also, during the first 11 days of February, DCA recorded more precipitation (3.78 inches) than it recorded during November 2017, December 2017, and January 2018 combined (3.44 inches).

For a nearly "normal" temperature month at DCA, January 2018 was quite interesting. While the average temperature of 35.7 degrees was only 0.3 below the 1981-2010 normal, the standard deviation of the 31 daily averages from the monthly average was 12.7 degrees. That's the highest standard deviation for any month since February 1996, which was 13.1 degrees (highest ever for DC was the lengendary month of February 1899, which was 15.6). Further, January 2018 precipitation was only 0.94 inches at DCA, the fourth lowest in January in DC behind only 1948 (0.31), 1872 (0.35), and 1981 (0.38). Moreover, for the five months ending in January 2018, precipitation totalled only 6.89 inches at DCA, the third lowest for that period in DC behind only September 1930-January 1931 (5.43) and September 2001-January 2002 (5.50).

February is normally relatively dry at DCA, although January is normally drier on a per day basis (average of 28.25 days in February vs 31 days in January). However, the last five months have been abnormally dry at DCA, with total precipitation totalling under 7 inches since September 1, 2017. Assuming that we receive no more than an inch or so between now and Wednesday, precipitation during September 2017 through January 2018 will be the third lowest total in DC for any September-January period (147 year record), behind only September 1930-January 1931 (5.43 inches) and September 2001-January 2002 (5.50 inches).

According to my records, yesterday's 41-degree temperature spread at DCA (62 maximum, 21 minimum) was the greatest since December 22, 1998 (67/24).

I just noted on the Capital Weather Gang discussion board that Kevin Benedict corrected one of my statements. The 13 days January 9-21, 1994 were slightly colder than the 13 days January 11-23, 1994 (21.2 vs. 21.8), and so our most recent 13 days came up 0.4 degrees shy of the coldest 13 consecutive days of January 1994. Also, January 9-22, 1994 averaged 21.6 degrees vs. 22.0 during January 10-23, 1994, and so our most recent 14 days came up 0.9 degrees shy of the coldest 14 consecutive days of January 1994. It is interesting to note, however, that while we came up just shy of beating the 13- and 14-day January 1994 cold streaks, we did surpass the coldest 13-day streak of January 1977 (January 11-23), which averaged 21.9 degrees at DCA. January 1977 was the 5th coldest January in DC history, at 25.4 degrees, compared with 28.8 degrees for January 1994, but it wasn't as intensely cold for any 13-day period.

As best as I can tell, the two weeks ending today at DCA are the coldest in nearly 24 years. Specifically, December 26, 2017 through January 8, 2018 averaged 22.5 degrees, and I can't find a colder two-week period since January 10-23, 1994, which averaged 22.0 degrees. That cold snap was highlighted by one of the coldest days in DC history-- January 19th -- which saw a maximum of + 8 and a minimum of -4, which was the last sub-zero reading at DCA. Moreover, if only the most recent 13 days are considered (December 27th to January 8th), the average was only 21.6 degrees, which was lower than the coldest 13 days in January 1994 (21.8 average during January 11th through 23rd). To find a colder 13 days than the most recent 13, you need to go back to December 15-27, 1989, which averaged 20.5 degrees.

Dulles fell below zero this morning for the first time since February 24, 2015. This morning's reading of -1 broke the record for January 7th of +1 that was set in 2014.

December 2017 at DCA came in at 39.2 degrees (0.5 below the 1981-2010 normal), and 2017 averaged 60.8 degrees, displacing 2016 (60.3) as DC's second warmest annual average temperature, behind 2012 (61.5). Similarly, December 2017 at IAD came in at 35.0 degrees (1.6 below the 1981-2010 normal), and 2017 averaged 57.2 degrees, again displacing 2016 (57.1) as IAD's second warmest annual average temperature, with 2012 again remaining the warmest (57.9).

Looks to be pretty much a done deal that 2017 will displace 2016 as second warmest in DC, despite the forecast of below normal December temperatures. As long as the DCA December temperature lands in a range of 34.2-47.3 degrees, 2017 will average in a range of 60.4-61.4 degrees. 2012 will remain warmest at 61.5 degrees. IAD also may finish 2017 as the second warmest, but that's more uncertain, as it would have to average between 34.3-43.5 degrees in December. The December average temperature there might fall below 34.3 degrees, and thus 2017 would fail to displace 2016 as the second warmest.

For October 2017 as a whole, DCA averaged 64.9 degrees, good enough for the third warmest October all-time in DC, with October 2007 the warmest at 67.0 degrees and October 1984 the second warmest at 65.2 degrees. At IAD, the average was 63.1 degrees, good enough for the second warmest October there, surpassed only by 2007 at 63.6 degrees.

October 9, 2017 didn't quite equal the previous day in this area, but nonetheless established new record high minimums in both DC and at IAD for this late in the year. At DCA, the minimum was 74 and at IAD was 69.

The DCA minimum yesterday (October 8th) was 75 -- by far the latest in the year that DC has had a minimum temperature that warm. The previous record-holder for a 75-degree or higher DC minimum late in the year was September 24th, when 75 was the minimum in 1970. So, this year's was two weeks later than that. Similarly, at IAD, yesterday's 73-degree minimum eclipsed the record for a 73-degree or higher minimum there this late in the year. The previous record-holder for a 73-degree or higher minimum there was September 9th, when 74 was the minimum last year. So, this year's was 29 days later, although last year's still holds the record for a late 74-degree or higher minimum there.

The 2017 astronomical summer here was considerably cooler, despite the warm finish. IAD averaged 73.5 degrees, down 4.5; and DCA averaged 77.6 degrees, down 3.5. The IAD composite summer averaged 73.4 degrees, down 3.7; and DCA averaged 77.43 degrees, down 2.74.

Right, although yesterday there were much higher rain totals not far from DCA. Still, I find it interesting that since I began this thread six and a half years ago, the same general pattern that existed for these two days prior to August 2011 has continued, albeit to a lesser extent; i.e., August 12th continues to be rainier than August 15th. Specifically, in the last seven years DCA has recorded 2.12 inches of precipitation on the 12th, but only 1.33 inches on the 15th. A very long-term coincidence, or something more?

This year featured rain on each day, with DCA recording 0.52 inches on August 12th and 0.17 inches on August 15th. So the updated totals, 1871-2017, are: August 12: 43.07 inches total; 21 days with a trace, 53 days with measurable, 12 days with at least an inch, 5 days with 2+ inches. August 15: 12.45 inches total; 16 days with a trace, 47 days with measurable, 5 days with at least an inch, no days with 2+ inches.

July 2017 at DCA finished with an average temperature of 81.7 degrees -- 12th warmest July of all-time in DC, but cooler than four of the previous seven. DCA also recorded 9.15 inches of precipitation in July -- 7th most ever in DC for that month, and the most July precipitation since the 9.44 inches in 1969.

I believe that DCA's precipitation total yesterday (3.31 inches) was the 6th highest daily July amount in DC history (record is 4.69 inches on July 9, 1970), and is also the most daily precipitation at DCA since Sandy (3.85 inches on October 29, 2012, which by the way fell 0.13 inches short of the October DC record set on October 4, 1877).

May 2017 had the distinction of being the first month in exactly one year to be: (a) below the 1981-2010 DCA temperature normal, finishing with an average of 65.5 vs. the May normal of 66.0; and (b) above the 1981-2010 DCA precipitation normal, finishing with 5.55 inches (assuming no more this evening) vs. the May normal of 3.99 inches. January-May 2017 monthly average temperature is 53.3, placing it second all-time in DC behind January-May 2012, which averaged 54.3.

In a May 1, 2017 Capital Weather Gang article (https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/05/01/washington-matched-records-for-the-warmest-most-humid-april-weather-this-weekend/?utm_term=.2d92d9f0a430), Jason Samenow notes that an average daily April temperature of 80.5 was also recorded in DC on April 20, 1941, with a maximum of 94 and a minimum of 67.

With the minimum touching 66 last night at DCA, the April 2017 average temperature there is corrected to 63.8, breaking the record by 1.8 degrees. January-April 2017 average held at 50.2 degrees, to break the first four-months high temperature record by 0.2 degrees.

Didn't happen, as the Weather Channel hourly forecast for DCA was way off-base, with the temperature there falling to 66 by midnight. So, April 29, 2017 remains the only April day in DC weather history to record a minimum of 70 or higher.

The NWS forecasts were pretty accurate, but the April 2017 DCA average wound up at 63.9 degrees, to break the DC record by 1.9 degrees. The January-April 2017 average was the same as forecast, at 50.2 degrees, to break the DC record by 0.2 degrees.

The new April DC high minimum of 70 set yesterday looks like it will be broken today, as the April 30, 2017 overnight low of 71 appears very likely to hold through midnight.