RodneyS

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.

April 29, 2017 one-upped Easter 2017 by breaking the all-time DC April minimum high temperature record of 69 set way back on April 19, 1896, with today's minimum of 70 at DCA. Today's maximum of 91 there tied the April 29th DC record set in 1974, but fell well short of the all-time DC April maximum record of 95 set on April 27, 1915 and duplicated on April 23, 1960, April 18, 1976, and April 17, 2002. However, today's average temperature of 80.5 also equaled the all-time DC April high average daily temperature record that was established on April 19,1896, which featured a maximum of 92 to go with the 69 minimum.

Using National Weather Service temperature forecasts for the remainder of April results in DCA finishing with an average April 2017 temperature of 63.7 degrees. That would break the April 1994 DC high average record by 1.7 degrees. Also, weighting the first four months of the year equally, January-April 2017 would average 50.2 degrees, breaking the January-April 2012 DC high average record by 0.2 degrees.

Easter 2017 (April 16th) did not establish an all-time high DC Easter maximum (95, set on April 18, 1976) nor an all-time high DC Easter minimum (66, set on April 6, 1947), but did tie the all-time high DC average Easter temperature with a maximum/minimum of 89/65 (average of 77.0), equal to the April 18, 1976 average (95/59).

You're welcome. With all the hype last month about March being colder than February, the cherry blossoms freezing, and the only half-way decent snowstorm of the winter occurring then, I'm guessing 90% of the Mid-Atlantic's population thinks it was an abnormally cold month. :-)

Are you sure? If you weight the first three months of 2017 equally, the first quarter average temperature at DCA was 45.7 degrees, which is third all-time in DC behind only 1Q 2012 (47.3) and 1Q 1990 (46.3).

The mid-March forecasts for the last half of the month at DCA missed the mark on the low side, as the final DCA March 2017 average temperature was 47.2 degrees. Half a degree cooler than February, but still above the 1981-2010 March normal of 46.8. In fact, it tied 1988 as the 49th warmest of 147 Marchs in DC history. Similarly, IAD averaged 44.2 in March 2017, which was 0.6 degrees below February, but exactly equal to the 1981-2010 March normal and tied with 2011 as the 25th warmest of 55 Marchs in IAD history.

The 2016-17 DCA astronomical winter wound up in second place all-time in DC, with an average temperature of 44.3 degrees. The composite winter averaged 43.7, finishing just behind last year and 4th all-time in DC.

The same holds true for DC. I just ran a projection for where March 2017 will finish at DCA based on a composite of the NWS, Weather Channel, and AccuWeather forecasts. The projected March 2017 average temperature works out to be 44.0, which would be 3.7 degrees colder than February 2017, but 1.9 degrees warmer than January 2017 and 2.2 degrees warmer than December 2016.

By the way, DCA's February 2017 average temperature of 47.7 is third all-time warmest for meteorological winter monthly temperatures in DC, behind only December 2015 at 51.2 and January 1950 at 48.0. At Dulles, the February 2017 average temperature of 44.8 is second all-time warmest for meteorological winter, behind only December 2015 at 48.7.

Here are the February 2017 average temperatures for DCA and IAD: DCA -- 47.7 degrees vs previous DC record high of 46.9 in 1976. IAD -- 44.8 vs. previous record high of 42.2 in 1990. IAD also broke its meteorological winter average high temperature record of 40.0 set in 2011-12, with a Dec-Feb average of 40.7. Finally, DCA broke its previous meteorological winter average high temperature record of 43.4 set in 2011-12, with an average of 43.8, but did not break the all-time DC record of 44.7 set in 1931-32 nor equal the 2nd place DC record of 44.3 established in 1889-90.

No record area highs today (both set in 2011 -- 77 at DCA and 74 at IAD), but IAD had an interesting distinction: The 47-degree temperature spread between the morning low of 25 and the afternoon high of 72 was the greatest there since April 8, 1995, when the temperature range was 34 to 81.