Dewpoints in DC over the year

Is it really that much more miserable outside in July? Why yes, it is. Here’s a graph of the monthly average, high, and low dew points at DCA.*


Dewpoint range & average at DCA in 2012

High, low, average dewpoint by month at DCA.


Ask people who don’t like hot, humid weather, and they’ll tell you that the weather measurement they rely on most is dew point.

Not temperature. Not relative humidity. Dew point.

“I think it’s catching on,” said meteorologist Paul Douglas. “It a superior way to, at a glance, determine what it really feels like out there.” Bill McAuliffe, Star-Tribune

I’m among those dew point fans. It, not the temperature or the heat index, best describes how it feels to be bicycling here. A hot and somewhat humid day may have a dew point of 70, identical to a cooler and off/on rainy day (of the sort we’ve had a lot of lately), but the net result is still getting drenched in sweat. My guideline for how I’ll feel when stopped (at lights, after riding):
<50 = no sweat, wear regular clothing
60 = nice, maybe change clothes at work
65 = acceptable but pushing it, go slow or get damp
70 = gross with sweat, definitely change shirt frequently
75 = I’d rather it rain, because either way I’m drenched
80 = instant dripping upon setting foot outside, tough to breathe
85 = kill me now, for surely Hades must be cooler than this

Update 13 July 2016: Capital Weather Gang has emoji’d this.

The article gives a good analogy: the dew point is the lowest temperature that it’s possible for sweat to cool your skin down to. I get uncomfortable at 70 and cranky at 80, and that corresponds nicely with the dewpoint guidance above.

The world’s highest dew points are around the Persian Gulf; high temps evaporate a lot of seawater into the air. The Plains and the South get high humidity mostly from plant transpiration.

I haven’t found the perfect weather app yet, so in the meantime I’ll dream of a 1×1 Android widget that displays what I really care about: dew point, wind speed/direction, and % chance of precipitation. Oh, and maybe temperature: at least one article (Jillian Strauss & Luis Miranda-Moreno, “Spatial modeling of bicycle activity at signalized intersections“) finds that humidity, then precipitation, then temperature determine cycling levels, even in cool Montreal.

Oh, and incidentally, this is one reason why I find European criticisms of how Americans dress while cycling to be so annoying. The average August dew point in Amsterdam? 58F (average monthly temperature is 64F). Their most humid August ever had a dew point of 72F, just above the *normal* dew point here. Of course they dress normally: they can. I spent several days biking around Paris during the catastrophic August 2003 heat wave; it was hot, with temperatures around 100F, but dew points were around 60F. That’s actually kinda nice weather by D.C. standards.

Which brings me to another pet peeve: the outdoors/activewear industry is overwhelmingly clustered in the West, which has much more courteous weather than the East or the South. Thus, “soft shell” outerwear appropriate for Cascadian drizzle leaves me drenched within minutes of venturing out into a thundershower, messenger bags pool up back sweat whereas back-saving panniers are hard to find, and everything’s much too casual for a city filled with dark suits. Most of humanity lives in the tropics, not in balmy Mediterranean or chilly North Sea climates, and it’s about time that fashion recognized that fact.

* Bear in mind that these are for entire months, days and nights, and that the high/low numbers are still averaged out over the course of an entire month, so individual days will certainly differ substantially. Also, to the extent that the region has microclimates, DCA probably has the highest dewpoints of the local airports with its low elevation, river frontage, and relatively high urban heat island exposure. Upland areas might be slightly more bearable.


Walking to DCA, and driving away

[Part of an occasional series of FAQs about traveling to Washington, D.C. For more, please click on the “dc-faqs” tag above.]

For those arriving/departing DCA on beautiful days like today, you might be interested in walking or cycling (perhaps using the marvelous Capital Bikeshare system) to DCA. It’s not just possible, it’s really pretty easy and fairly well signed. Indeed, it may be America’s most pedestrian friendly major airport. Note that there are multiple approaches, depending on where you’re coming from and where you’re going.

It takes about 20 minutes to walk to the airport from the nearest points of interest, which are Crystal City or Gravelly Point.

Where you’re going:
Concourse A is at the south end, Concourse C is at the north end, and B is closer to the north. Higher gate numbers are north.

As of this writing, US Airways is at the north end (C/B), American and Delta and United in B, and everyone else in A.

Where you’re coming from:
1. From northern Crystal City, via the Mount Vernon Trail access at the Water Park/18th St. S., this map shows two route options:

DCA walk/bike access route

The yellow route is the signed route from the Mount Vernon Trail, without any grade crossings. It’s reasonably direct for cyclists approaching from the south, but for pedestrians from the north it adds almost 1/2 mile (and even more for people headed to the south pier or Terminal A).

The red route is much more direct for those coming from Crystal City (to the north) but requires jaywalking across a three high-speed roads, each one 1-2 lanes and with okay sight lines. Use extreme caution.

2. From southern Crystal City, or for the south end of the airport (Terminal A, south parking garage & car rentals), start at the sand volleyball courts and walk along the northbound exit ramp, over the Airport Access Road bridge, and follow the signs around the offices to the terminal.

There is a Capital Bikeshare kiosk next to the sand volleyball courts.

3. From points north along the Mount Vernon Trail, like Rosslyn, D.C., and Gravelly Point, you can also exit the Mount Vernon Trail into the airport employee parking lot at the airport’s north end. (There are usually US Airways Express regional jets parked behind the fence here, right next to the trail.) Just follow the sidewalk alongside the airport offices to Concourse C.

(Another transportation option: Gravelly Point has a small boat launch; I’ve docked an inflatable kayak there, then walked it the one mile to DCA’s Metro station.)

4. From points south along the Mount Vernon Trail, the trail directly crosses a spur to Aviation Circle at the airport’s south end, by the Signature Flight Support building. Just exit the trail there and head north along Aviation to the concourses.

Once you’re on airport grounds, there’s adequate signage along the walkways, several outdoor bike racks, and a shuttle bus connects the concourse curbsides, rental car center, and Metro entrance. In most cases, walking is just as fast as waiting for the shuttle.

Driving away

DCA’s easy accessibility opens up another multimodal possibility: car rentals. In particular, Hotwire and weekend-special rates from DCA can often be found for around $10-15 (+ required fees = $30); these rates are generally available Friday morning to Monday morning, and sometimes at the last minute on weekdays.

If you prepay online, check-in takes a few minutes at an automated kiosk, and the cars are parked upstairs; the entire process takes about 10 minutes. The car rental center is in the south parking garage, across from Concourse A and near the south exit of the Metro station (map).

Flying in: the river visual approach


The flight approaches to DCA fly over the Potomac River, in order to avoid noise impacts over the city and to avoid flights over “P-56” (aka the Monumental Core). If winds are from the south/east, flights will land from the north and take off to the south. Planes are closer to the ground during landing than during take-off, so if you have this landing you’ll be treated to fantastic views of central D.C. (on the left side) and Arlington (on the right side) in the last few minutes of flight.

As a planner, I find it fascinating to watch the cityscape unfold:
– the topographical shift, from hilly up by Great Falls through to Georgetown, then the coastal flats below
– the formal straight lines of the Mall and L’Enfant Plan, reinforced by the dense built fabric, and on the other side the curves of Arlington Cemetery and its riverfront roads
– tracing the lines of activity and development along roads like Wisconsin and Connecticut, and the Metro subway lines
– the D.C. skyline of public monuments and churches, and how close planes fly to Rosslyn’s office towers
– further out, the clear distinction between preserved farmland in Maryland and suburban sprawl in Virginia

Where are some hotel values around D.C.?

[Part of an occasional series of FAQs about traveling to Washington, D.C. For more, please click on the “dc-faqs” tag above.]

Washington is a huge destination for business travelers, so hotels tend to be expensive. If you are at all flexible in the times that you can visit, you can find much better prices on hotels on weekends and during Congressional holidays — particularly in August and around Christmas, Thanksgiving, and other major holidays. Transient Washingtonians tend to leave town to visit families elsewhere during major holidays and even summer weekends.

The most reliably affordable, quality (3* to 5*) hotels are those in Arlington’s Crystal City neighborhood, often marketed as being near National Airport. There are thousands of hotel rooms there, with most major U.S. chains represented, and except during conventions or other big events (cherry blossoms, Independence Day, Memorial Day) they rarely sell out. That means that you can often use Hotwire or Priceline to get low rates.*

What’s more, Crystal City is very conveniently located right on two Metro lines, less than 15 minutes from the Mall. It’s also just off I-395 and offers free weekend garage parking. Capital Bikeshare docks around the neighborhood make it easy to get onto local trails or to shops in neighboring Pentagon City. Arlington is almost laughably safe.

The downside is that it’s not the most scenic neighborhood: it’s almost entirely concrete towers from the 1970s and 1980s, and interior renovations haven’t appreciably improved that aesthetic. Since the surroundings are mostly offices, it’s really quiet on evenings and weekends. There are a few restaurants there, so you won’t go hungry, and there’s a mall half a mile away at Pentagon City, but most locals will stifle a yawn at the very mention of “Crystal City.”

Just on the other side of the city, Silver Spring has a few hotels. It’s a livelier area than Crystal City, but historically their rates have been higher as well.

Within the city, the prime neighborhoods within or adjacent to downtown (including Dupont, West End, and Georgetown) often move in lockstep, so there are few bargains to be found. Dupont has some quirkier boutique options; Kimpton Hotels, in particular, has converted several 1960s studio apartment buildings in the neighborhood into themed hotels that have quite spacious rooms, if spare common facilities.

There’s a cluster of cheap motels along New York Avenue NE; these hotels often market themselves as “near Union Station.” Beware of the low prices: NY Avenue is a loud, busy highway that offers little connection to the rest of the city, and some of these hotels have a seedy reputation.

Similarly, there are dozens of hotels around the other two large airports, Dulles and Baltimore-Washington. These are generally very inconvenient to D.C.: getting to/from town requires going to the airport, then paying extra for transit service into town. I’d book a room near BWI before Dulles, and even then it would have to be at a steep ($50+) discount to justify the added travel time and cost.

You can also, of course, look for alternative lodging arrangements like AirBNB** or Couchsurfing or even camping.

* Affiliate link to BetterBidding, a useful site if you want to try and discern the identity of a hotel before you bid
** Affiliate link that could benefit me, but probably won’t

A weekend in Washington

[Part of an occasional series of FAQs about traveling to Washington, D.C. For more, please click on the “dc-faqs” tag above.]

Unlike other cities, you’re here in Washington not to understand a city, but to understand a country, so there’s no way that I would recommend that someone skip the usual monumental sights. Let’s start with what the experts recommend.

To which I’d add these personal favorites among the monuments, memorials, and museums — although bear in mind that most people find what I’m interested in to be terribly boring, so you should take the time to find the things that interest you:

  • since I volunteer at the National Building Museum, I can vouch for its amazing space, thoughtful (and fun) exhibits, and fascinating museum shop; other architecture geeks might also see what’s in the windows at the District Architecture Center
  • the Smithsonian American Art Museum: be sure to spend time curating your own art experience at the library-like Luce Center on the third floor, and stop in to admire the magnificent Renwick Gallery across from the White House
  • the Library of Congress has consistently fascinating public exhibits, and getting a reader card to explore the reading rooms’ vast reference collections — and just maybe request a book, any book — takes just a few minutes
  • the National Gallery of Art’s East Wing has a tremendous collection of Calder mobiles, housed in a soaring space tucked into a corner of the concourse-level gallery
  • most assume that the Smithsonian’s collections of Americana would overshadow its collections about the rest of the world, but in fact its connected Freer, Sackler, and African Art museums have some of the finest collections in their respective fields anywhere
  • whenever I’m feeling homesick for Chicago, the simulated “L” ride at the American History museum takes me right back to the Loop
  • between the Kennedy Center, nearby cinemas (from Hollywood blockbusters at Georgetown AMC Loews to indie documentaries at West End), natural Theodore Roosevelt Island, and a waterfront park boasting both pubs and boathouses, there’s something for all tastes along the Foggy Bottom-Georgetown waterfront
  • if a Hollywood blockbuster is showing at the Smithsonian’s [trueImax screens, it’s really not worth seeing anywhere else (plus, these are the closest cinemas to my house, not counting the outdoor film fests that have movies every night all summer)

I also find the monuments at the west end of the Mall to be too widely spaced for a comfortable walk. Instead, use bike share and this handy Monuments by Bikeshare route, which uses  off-street paths or low-traffic roads. For a great look at the city behind the monuments, the “13 Colonies Ride” is an excellent place to start.

Leaving your luggage in Washington

[First in an occasional series of FAQs about traveling to Washington, D.C. For more, please click on the “dc-faqs” tag above. Information verified current as of September 2014.]

Left-luggage facilities are fiendishly difficult to find in the USA. Security overkill accounts for some of that, sure, but countries with far more experience with train-station terrorism still have plenty of luggage lockers.

First up: it can’t be repeated enough, but pack light. Not having to wrestle with lots of luggage means much greater flexibility. Carry as little as possible while sightseeing in Washington, and in particular, keep metal objects to a minimum. Airport-style security checks are commonplace: you will walk through a metal detector, and someone will poke through your bag. During the summer, many museums will have long lines to have bags examined, but no lines for persons. I’ve never encountered a line when carrying the absolute minimum of wallet + phone, no jewelry, no belt.

Small bags can be checked at several Smithsonian museums and must be checked at the National Gallery of Art. Just be sure to remove anything that might raise a security guard’s eyebrow, and queue up to retrieve them before the closing-hour rush. Note that Gallery Place has small lockers and closes at 7PM, not 5PM like most of the other museums. The Udvar-Hazy Center, near Dulles airport, has larger lockers that can fit most carry-ons.

If you’re departing or arriving by train and don’t need your bags overnight, Amtrak allows passengers to check bags in a day before, or to pick up checked bags days after arrival. The key caveats: relatively few stations have baggage service, and on the Northeast Corridor, bags only go on the overnight train (so you’ll have to check your bags the night before or retrieve them the day after). To retrieve your bags after the fact, go to the information desk and have them call a baggage attendant; have your claim check ready.

Similarly, you can usually check bags for airline flights anytime on the day of travel. This would be a tremendous time-suck in most cities, but it’s easily done for flights from nearby DCA.

Hotel bellhops check bags for arriving/departing guests as a courtesy, and if you play your cards right you can usually take advantage of this. Dress like a business traveler, tip generously, and don’t lie if asked. You’re best off trying large convention hotels where the bell desk is outside the lobby (not smaller hotels where it’s at the front desk); walk into a side door of the hotel and out the front door to the bell desk.

One last resort is the left-luggage facility at Union Station, next to the MARC commuter rail gates. It’s expensive, but it’s also right there.