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Posted at 5:50 PM ET, 07/ 6/2010

PM Update: Heat wave keeps area boiling

By Ian Livingston

Another day near 100 Wednesday before slight break

* Thinking cool | D.C. fireworks | Heat chat | Weather Wall | NatCast *
* Stay cool with a CWG Snowmageddon t-shirt: Check it out *

UPDATE, Today's highs: DCA 102, IAD 100, BWI 105 (record)

Hot days tend to climax in the afternoon, but on this first of two heat advisory days we (and much of the northeast) have been "treated" to 95-100 degree heat since before lunchtime. A scant number of clouds are creating some shade, but that doesn't help much when it's this hot! BWI -- which was 105 at 4 p.m., obliterated its old record for the day of 101 (1999). Before the day is out, other local records may fall as Reagan National has reached at least 102 (record is 103). Saving grace: low to moderate humidity. So, the heat index isn't much higher than the temperature.

Temperatures: Latest D.C. area temperature map powered by iMapWeather (base map by Google). Click and hold on map to pan. Double-click to zoom. Refresh page to update. See larger map on our Weather Wall.

Through Tonight: This is not the best evening to do much outside. Though a setting sun will provide some relief, temperatures at sunset should still be in the low-to-mid 90s. Overnight lows fall to the mid-70s in the suburbs to around 80 in the city. At D.C., the record highest overnight low for the date of 79 should be threatened.

Tomorrow (Wednesday): The setup for tomorrow is almost the same as today so results should be as well. Clouds that were few and far between most of today could end up slightly more numerous tomorrow, and that could hold temperatures down a hair. Nonetheless, highs in the upper 90s and low 100s are a good bet. Humidity levels should also start to come up and would make up for any potential apparent temperature difference.

See Matt Rogers' forecast through the week. And if you haven't already, join us on Facebook and follow us on Twitter.

100-degree days: This is D.C.'s second 100+ day of the year (just missed with two 99s as well). 25 seasons since records began have now reached this mark, 2002 being the most recent. If we can get our third day tomorrow, we'll be up with only 10 other years on record and have plenty of summer to go. Baltimore-Washington has now hit 100+ four days this year, including today's high which ranks in the top 10 hottest days all time. If that location hits 100 or higher tomorrow it will be the first time since 1966 it has recorded three days in a row at that level and one behind the all-time leader 1930.

By Ian Livingston  | July 6, 2010; 5:50 PM ET
Categories:  Forecasts  
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Next: NatCast: Home team would gladly hit the road


Made it up to at least 102 degrees F in The Baked Apple. I remember that 1966 heat wave all too well. We went to see The Ten Commandments on July 4, when the DCA was 101. The theatre turned off the a/c part-way through the show. We were totally emphathetic with the Hebrews as the struggled through the desert.

One way to keep cool: watch the World Cup, where people are using lap blankets this evening in Capetown.

D.C.'s Snowmageddon was exactly five months ago, today, was it not? Hopefully we'll see more flakes in just about five months hence.

Posted by: JerryFloyd1 | July 6, 2010 3:29 PM | Report abuse

Reposting part of the above with a few minor cxs...

Made it up to at least 102 degrees F TODAY in The Baked Apple.

I remember that 1966 heat wave all too well. We went to see The Ten Commandments FILM on July 4, when the DCA HIGH was 101. The theatre turned off the a/c part-way through the show. We were totally empathetic with the Hebrews as they struggled through the desert.

Posted by: JerryFloyd1 | July 6, 2010 3:34 PM | Report abuse

From CWG chat today:

Washington, D.C.: Is this extreme heat a result of Global Warming?

Matt Rogers: The record highest temperature for July in DC was 106F set in 1930. The record highest temperature for August was 106F set in 1918. The theory on global warming is that heat waves should become more frequent (see Andrew Freedman's post today on our blog), but as a meteorologist, I know that we see more heat waves on the East Coast when a La Nina is developing in the Pacific as it is doing this particular year.

From Bill McKibben

The accelerating rise in temperatures in the years since The End of Nature was published means that 1988 is now the fifteenth warmest year on record. Seventeen of the twenty warmest years have been in the 1990s and 2000s.

Posted by: sugarstreet | July 6, 2010 3:38 PM | Report abuse

I used to remember being in DCA back in 1992-1996 and would put up with the heat as well as the cold.

How many would remember on a March day when we got the nice warm weather in the morning and then by mid afternoon it would turn cold and snowing that late evening? I would laugh at people who wore shorts that day.

Posted by: beeker25 | July 6, 2010 3:55 PM | Report abuse

Shocking: BWI hits 105 at 4 pm, DCA 102, IAD at 98.

Posted by: CapitalWeatherGang | July 6, 2010 4:00 PM | Report abuse

That 105 at BWI now makes this tied with 4 other times for second hottest reading. 107 is hottest.

Posted by: Ian-CapitalWeatherGang | July 6, 2010 4:05 PM | Report abuse

Just wondering, how many days are there on record when it has gotten up to 100 degrees or more in DC? And over how many years is that? After living in the DC area most of the last 30 years, I know that we come close to the "century mark" a lot more often than we break it.

Also, how many of those days has it gotten up to 102 as it has today? How many higher than 102?

Posted by: lkusmin | July 6, 2010 4:10 PM | Report abuse

i've gotta say....this is just about the most comfortable 102 degrees i remember. i remember plenty of 95 degree days that felt worse.

Posted by: walter-in-fallschurch | July 6, 2010 4:15 PM | Report abuse

@lkusmin, I'm pretty sure the temps reached 100 or more six times in 1980 but CWG has access to all the data.

Posted by: JerryFloyd1 | July 6, 2010 4:16 PM | Report abuse


Kinda agree. Was out earlier and didn't seem that bad.

Posted by: CapitalWeatherGang | July 6, 2010 4:16 PM | Report abuse

indeed...hopefully our quasi-annual dec 5 storm turns out to be a big one!

Posted by: walter-in-fallschurch | July 6, 2010 4:17 PM | Report abuse

I don't mind the heat when we also have low humidity like right now. Reminds me of the desert areas out west, the heat never seems as bad there as August in DC is even if the temps are technically higher.

Posted by: kallieh | July 6, 2010 4:22 PM | Report abuse

Like lots of others, I miss snowmageddon. I am prepared now since the snow boots I bought came just in time for the snow to end. Bring it on!

Posted by: BruinGirl2001 | July 6, 2010 4:27 PM | Report abuse

i miss the cold and snow! this is way too hot.

Posted by: madisondc | July 6, 2010 4:30 PM | Report abuse

lkusmin, since 1872 there have been 102 days at or above 100 (including the 2 this year). There have been 31 102 or higher in that time frame, 12 since the measuring location was switched to DCA in the 40s. If we hit 103 offhour it would be the 18th time at that temp or higher since 1872.

Posted by: Ian-CapitalWeatherGang | July 6, 2010 4:34 PM | Report abuse

I too have noticed the lower humidity than the last heat wave a few weeks ago. The night temperatures can get a few degrees cooler and that does make a difference.

Also, my rule-of-thumb for hot summer days is holding true. Whatever the temp report on the radio in the morning is (around 7:00 when I'm showering), it gets about 20 degrees warmer. They were reporting 79 to 80 downtown this morning.

Posted by: LouLewis | July 6, 2010 4:37 PM | Report abuse

This and the last heat wave are not that dissimilar actually, though this one will probably end up shorter even if it’s only a day or two sub 90 before they return. Some keep referring to the Bermuda High which I think it slightly misleading in that the heat source is originally off the continent, hence the lower humidity levels. We have indeed seen some tropical humidity work in from time to time as surface highs slip off the coast but the Atlantic high is not the primary driver so far this year.

Posted by: Ian-CapitalWeatherGang | July 6, 2010 4:41 PM | Report abuse

I remember a night in Aug of 2007 that was unbearable at 11:30 PM, it was like a sauna, Does anyone remember this? Gang? It was a Saturday night in early Aug of 2007 I believe. That...was...brutal..

Posted by: jrodfoo | July 6, 2010 4:44 PM | Report abuse

What's the record for 100 degree days in a summer?

Posted by: ah___ | July 6, 2010 4:48 PM | Report abuse

3rd snowiest winter, maybe we can go for the 3rd hottest summer?

Posted by: paul-Sterling | July 6, 2010 4:49 PM | Report abuse

105. Wow. Being a native Arizonan, I must agree that walking outside this afternoon felt a bit more like Phoenix than DC. Humidity really does make a huge difference.

So does concrete. The Urban Heat Island effect is very pronounced today...forested areas feel dramatically cooler than pavement. Have any of you noticed this too?

Posted by: Ann-CapitalWeatherGang | July 6, 2010 4:56 PM | Report abuse

ah___: At DC 1930 had 11, 1988 had 7, 1980 had 5 (plus 1 in the fall for 6), 1997 had 5, there are three years with 4 100+ and two with 3 days 100+.

Posted by: Ian-CapitalWeatherGang | July 6, 2010 5:00 PM | Report abuse

@jrodfoo - That was the first thursday of August, 2007. It was the night of the National Night Out celebration that the neighborhood watch folks put on every year. Brutal.

Posted by: chris_soule | July 6, 2010 5:01 PM | Report abuse

@Ian, my recollection is that the last of the six 100 degree days in 1980 was on the first day of fall, when it reached 101.

As noted in a post a few days ago, the 10 highest temps that toasty summer averaged exactly 100 degrees.

Posted by: JerryFloyd1 | July 6, 2010 5:05 PM | Report abuse

...and IAD finally joins the century club today!

Posted by: Brian-CapitalWeatherGang | July 6, 2010 5:08 PM | Report abuse

I love this weather! Waited all winter for it...

Posted by: rumbly45 | July 6, 2010 5:09 PM | Report abuse

@Ann- just drove from NE DC to NW. Car thermometer read 105 briefly on open pavement on Missouri Ave, then down to 97 in Rock Creek Park, 101 in more shady neighborhoods off Connecticut Ave.

Posted by: dhb2 | July 6, 2010 5:10 PM | Report abuse

JerryFloyd1, yep sep 21 and 101. I was referring to meteorological seasons with that post (not that it really matters as only 4 seasons have had 100 outside June-Aug). That's the latest 100+ on record at DC by about 10 days.

Posted by: Ian-CapitalWeatherGang | July 6, 2010 5:16 PM | Report abuse

Forested areas are definitely dramatically cooler. I live on some acreage in semi-rural AA Co., MD. Just walking from open pasture to under a canopy of tall trees feels like a 15 degree drop in temp. Anyone who wonders about the protective effect of forests should try a little walkabout in the woods on days like this.

Posted by: thingsfallapart | July 6, 2010 5:25 PM | Report abuse

@Ian, thanks for verifying that 101 reading in 1980. The 10 hottest days where the high averaged 100 degrees may have been 1987, not 1980.

NYC and Newark both set new daily records of 103 today.

I worry for the folks working at the Foggy Bottom Farmers Market tomorrow afternoon. Baked berries!

Posted by: JerryFloyd1 | July 6, 2010 5:29 PM | Report abuse

@thingsfallapart that is called share. he was referring to grassy areas being colder than streets and concrete areas like the city. im sorry but you fail

Posted by: samd95 | July 6, 2010 5:29 PM | Report abuse


Posted by: samd95 | July 6, 2010 5:35 PM | Report abuse

Anyone care to share their shade?

Posted by: eric654 | July 6, 2010 5:36 PM | Report abuse

Forecast for the next few days - it has been changing wildly. Just when it looked like starting Thursday we were going to get a big break now it's back to a high of 94. Then heat if back on next Wednesday.
Still no solid rain chance.

Posted by: LoudounGeek | July 6, 2010 5:43 PM | Report abuse

JerryFloyd1, I think you were right about it being 1980. The top 10 highs average 100F, though there were 4 more highs of 98 (same as some in the top 10). If you avg the 14 days 98+ it was 99.5.

Posted by: Ian-CapitalWeatherGang | July 6, 2010 5:46 PM | Report abuse

NYC in 1988 had a high of 108 degrees, and it was about this same week actually.

Posted by: blasmaic | July 6, 2010 6:04 PM | Report abuse

Thanks for the warm welcome, samd95. I never knew what that less sunny area under the tree canopy was called. But for the record, the "forested areas" not under the trees are cooler than the heavily paved areas as well. Have a pleasant evening, and enjoy your electric bill.

"The Urban Heat Island effect is very pronounced today...forested areas feel dramatically cooler than pavement. Have any of you noticed this too"

Posted by: thingsfallapart | July 6, 2010 6:16 PM | Report abuse

Doesn't it seem that most weathercasters are very conservative with their forecasts? Weatherbug today was calling for a high of 92 or 93 at my location (Shady Side, MD), but shows that we actually hit 102.

Tomorrow they're outright calling for 101. Uh oh.....

Posted by: ChickenLady | July 6, 2010 7:46 PM | Report abuse

I did the "Fry and Egg on the Pavement" test today. Here is the link on YouTube! The results were quite amazing!


Posted by: stinkerflat1 | July 6, 2010 7:51 PM | Report abuse

Today was the Aphelion when the earth is farther from the sun than at any other day of the year!

Posted by: mgb711 | July 6, 2010 8:39 PM | Report abuse

mgb711 - hard to believe that here in the northern hemisphere, we are LUCKY to have the earth's orbit around the sun be the furthest away simultaneous with our hemisphere's tilt toward the sun during our summer. I feel bad for the southern hemisphere sometimes ;) but we are certainly hot enough without more solar input!

Posted by: Camden-CapitalWeatherGang | July 6, 2010 8:47 PM | Report abuse

@Ann - as a bike commuter, I notice this a lot. I work in Springfield, and coming off a small road with lots of trees and shade (newington) onto a large road with trees far off to the side (telegraph) it was like hitting a wall of heat. I bet the temp difference was a solid ten degrees in a matter of feet.

Posted by: debiguity | July 6, 2010 8:57 PM | Report abuse


That was too funny..I forwarded it to family all around. In 2002 I was in Las Vegas in August and it was in the low 100's. As I walked down the sidewalk I noticed a fried egg on the sidewalk!! Perhaps yours would have cooked quicker if it was directly on the sidewalk as well ;0) Thanks for the laugh.

Posted by: worldtraveler83 | July 6, 2010 9:32 PM | Report abuse

dang...that fry-an-egg thing was a bit of a let down. i had such high hopes.... you know, if you must do it (heh heh) in a frying pan, maybe you should have left the pan out in the sun for an hour or so BEFORE putting the egg in it - so it would be nice and hot when the egg went in?

Posted by: walter-in-fallschurch | July 6, 2010 9:42 PM | Report abuse


watched your link this a.m. when you were on tv with your shark sculpture and just finished your link with Jon Stewart. That was a cool reminder on a too hot day. Like you, just passing the time till that white stuff starts falling. Keep "cool" thoughts or better yet, eat some ice cream!

Posted by: worldtraveler83 | July 6, 2010 9:52 PM | Report abuse

Well, it is hot and dry. A deer ran across the backyard this evening and the ground is so hard it sounded like a horse galloping across the desert.

Down to 78 so far after a high today of 94 on the mtn...

Posted by: spgass1 | July 6, 2010 9:56 PM | Report abuse

you know...i told that reporter the shark was 27' long (i measured), but he reported it as 20' long... sadly, i fear it will be a while before i can make a 27' long sculpture... but i'm ever hopeful... and, as JerryFloyd1 mentioned, only 5 months 'til the dec 5 snowstorm!

Posted by: walter-in-fallschurch | July 7, 2010 12:20 AM | Report abuse

thanks for confirming Ian. had forgotten about the top 14 days coming in at 99.5. truly awful but it was mostly a dry heat that summer so not as intolerable as today may be.

Posted by: JerryFloyd1 | July 7, 2010 6:24 AM | Report abuse

Camden, it's an interesting "what-if" question. The world on average is about 4C warmer in our winter than in our summer. With no other changes we would be 3 or 4 degrees F higher so we would see a lot more 100 degree days like yesterday. 3-4 colder in the winter also.

But there would almost certainly be radical changes if we switched tilt the other way. The NH has a lot more land mass which would bake in the summer and freeze solid in the winter causing dryness. The lack of evaporation in the SH with weaker SH summer sun would exacerbate that dryness. Despite brutally hot summer sun, the ice sheets would probably take over due to a drier atmosphere worldwide with a greatly reduced GH warming effect.

Posted by: eric654 | July 7, 2010 7:05 AM | Report abuse


Reflecting the long-term warming trend in the Earth's climate, U.S. and global annual temperatures are now approximately 1.0°F warmer than at the start of the 20th century, and the rate of warming has accelerated over the past 30 years, increasing globally since the mid-1970's at a rate approximately three times faster than the entury-scale trend. For additional information on global emperature trends, please see the 2006 annual temperature trends discussion.
U.S. Annual Temperature timeseries

The last eight 5-year periods (2002-2006, 2001-2005, 2000-2004, 1999-2003, 1998-2002, 1997-2001, 1996-2000, 1995-1999), were the warmest 5-year periods (i.e. pentads) in the last 112 years of national records, illustrating the anomalous warmth of the last decade. The 9th warmest pentad was in the 1930s (1930-34), when the western U.S. was suffering from an extended drought coupled with anomalous warmth. The three warmest years on record are 1998, 2006 and 1934. In 1998, the record warmth was concentrated in the Northeast as compared with the Northwest during 1934. In 2006, much above average temperatures were present across most of the U.S. The West Coast and parts of the Ohio Valley and Southeast were above average. No state was near or below average for 2006.

From NOAAA 2006 report (US)

Posted by: sugarstreet | July 7, 2010 7:21 AM | Report abuse

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