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Posted at 4:15 PM ET, 07/18/2010

Forecast: Heat locked in, humidity to get worse

By Dan Stillman

* Blizzards, heat waves... earthquake? | Storm that saved D.C. *
* Outside now? Radar, temps & more: Weather Wall | UnitedCast *
* Consec days of 90+: 5; Total 90+: 35 (Apr: 2; May: 3; Jun: 18; Jul: 12) *

Today's Daily Digit
A somewhat subjective rating of the
day's weather, on a scale of 0 to 10.


No discernible change from Saturday's heat & humidity. So no change to the digit.
Get the 'Digit' on Twitter


Today: Partly sunny & humid. Small chance of p.m. storm. Mid-90s. | Tonight: Partly cloudy & muggy. 70s. | Tomorrow: Partly sunny. 40% chance of p.m. storms. Low-to-mid 90s. | A Look Ahead | Get Express Forecast by E-mail


So, which kind of heat wave do you prefer? The one earlier this month that featured attention-grabbing highs near and over 100, but only moderate humidity with no rain? Or the current one, which is more of the mid-90s variety but humid (and increasingly so it appears) with occasionally decent shower/storm chances? You know it's a rough summer when these are your choices. Can't decide? With no end in sight to this latest heat wave, you'll have plenty of time to consider.

Radar & lightning: Latest D.C. area radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Today (Sunday): Virtually the same as yesterday -- partly sunny, hot and humid with highs in the mid-90s. An isolated storm or two could pop up in the afternoon or early evening. But the odds of seeing one at any particular location are only around 15-20%, except closer to 25% for areas south and east of the Beltway. Winds from the west at about 10 mph. Confidence: Medium-High

Tonight: We're partly cloudy with maybe an isolated early-evening storm. Some of the cooler suburbs may make it down to the low 70s for overnight lows, while most other places bottom in the mid-to-upper 70s. Everyone gets the same level of relentless mugginess. Confidence: Medium-High

Keep reading for the forecast through midweek...

Tomorrow (Monday): A new work week brings the same old weather, at least to start the day, as temperatures begin their climb toward highs in the low-to-mid 90s under partly sunny skies. Skies may cloud over by late morning with a 40% chance of showers and thunderstorms during the midday into evening. Confidence: Medium (Updated: Sunday July 18 @ 11:35 pm)

Tomorrow Night: A 30-40% chance of showers/storms lingers into the evening. Even if you don't get rain where you happen to be, you'll feel the moisture in the air in the form of very high humidity. Overnight, temperatures stall out in the 70s again for lows. Confidence: Medium


If there's anything different about Tuesday and Wednesday, it'll be even higher and more uncomfortable humidity, to go along with highs in the low-to-mid 90s, a 30% chance or so of afternoon/evening thunderstorms, and nighttime lows in the 70s. If all goes as planned, Wednesday would be our eighth straight day at or over 90, with likely more to come. Confidence: Medium

By Dan Stillman  | July 18, 2010; 4:15 PM ET
Categories:  Forecasts  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: UnitedCast: Seriously warm soccer
Next: Some Sunday evening storminess


"So, which kind of heat wave do you prefer?"
That is easy. I prefer the 100's with less humidity. The "heat index", "real feel" or "humiture" is a fallacy. It is a formulated attempt to convince us a certain temperature and humidity level really feels like a different, higher temperature. It is based on responses to individuals who have been asked how they feel under certain temperature/humidity readings. Quite subjective. To me, 105 and relatively low humidity is more comfortable than 95 with high relative humidity. The last time we hit 100 in DC I could sit in the yard, in the shade with the slightest of breezes, and be relatively comfortable. When it's like it has been recently, just checking out the garden is a sweaty hell. Has anybody seen the formula used to give us the heat index? From a simple questionnaire comes a formula so long it makes one dizzy. This is not to say that 105 is not hot. It is. But I believe it is much more tolerable than the weather we are experiencing now and especially over the next few days. Just my (relative) 2 cents.

Posted by: pjdunn1 | July 18, 2010 8:16 AM | Report abuse

Even though the dry heat feels less oppresive to me (but I hate hot weather in general), it doesn't offset the pain of writing checks to nurseries and/or WSSC during these dry summers. Sometime we'll have to do a cost comparison of summer drought watering bills to Bombo's shoe replacement bills during rainy weather! ;-)

Posted by: ftwash | July 18, 2010 8:55 AM | Report abuse

If you're taking a poll, I prefer drier heat. As I always tell newcomers to the area, it's not the temps that get you, it's the dewpoints. When it's 103 and the dewpoint is in the 50s, like last month, you can still walk a couple blocks downtown no problem; you can still sit by the pool and enjoy summer. When it's 93 and the dewpoint is in the 70s, just forget about it. You'll want to take an air-conditioned taxi just to cross the street. Dry heat is invigorating; sticky heat is debilitating.

Posted by: fleeciewool | July 18, 2010 9:47 AM | Report abuse

these posts where CWG tries to make some sort of emotional statement about the weather are getting more tiresome than the weather itself

if Brauchli and the Post execs have this 20th century view that you can't present data without adding a lot of personal stories and emotion, I suggest they look at the traffic for the weather sites, especially weather underground, that just give you the facts and NWS forecast, no hype

I've always liked CWG, but lately it's getting a little too with the overly emotional stories about temps that are just 3-5 degrees above average, please stop

Posted by: tgt111 | July 18, 2010 10:34 AM | Report abuse

Blah blah blah, technorati, quit complaining. If you don't want commentary mixed in with the forecast, go to People read here because it has locally-focused discussions that are often infused with the realistic human dimension of coping with the weather.

Per the topic at hand - I grew up in Florida, and the heat this summer up here has been nearly as bad if not worse than the worst summers growing up. Without the ocean breeze or the afternoon t-storms, this area is one gross, sweaty greenhouse.

Posted by: SWester2010 | July 18, 2010 11:25 AM | Report abuse

My apologies, brain fart (thanks to the heat?). My comment was addressed to tgt111...

Posted by: SWester2010 | July 18, 2010 11:26 AM | Report abuse

Warmest first half of year on record
by Jonathan Erdman, Editorial Meteorologist

NOAA's National Climatic Data Center reported Thursday global land and ocean surface temperatures in the first six months of 2010 were the warmest January-June on record. Records date back to 1880.

June was the fourth straight warmest month globally, following a record warm March, April, and May around the globe.

The last month with global temperatures below the 20th century average, according to NOAA, was over 25 years ago, February 1985.

Posted by: sugarstreet | July 18, 2010 11:34 AM | Report abuse


The warmest full year on record, globally, is 2005.

But there is no global warming. Remember that.

Posted by: sugarstreet | July 18, 2010 11:35 AM | Report abuse

I don't know what to make of those "warmest x in history" stories. Reliable records only go back a hundred years at best, and the measuring of temps was not as accurate in the early parts of this time period as they are now. Even now such measurements are sort of suspect given, as a big case in point, the measurement of snowfall this winter at National versus other parts of the region, and what happened in Baltimore.

Another case in point, I think, is the measurement of the shrinking of the arctic ice cap. It's the "lowest sea ice extent ever measured during summer," but we've only been able to measure it for 25 years. The perspective seems a little off. Cause for concern? Probably. Alarm? I think the jury's still out on that one.

Posted by: AdmiralX | July 18, 2010 12:01 PM | Report abuse

Clouds have been keeping the temp down here in Centreville. Right now I'm at 88 very muggy degrees.

Posted by: FIREDRAGON47 | July 18, 2010 1:27 PM | Report abuse

ftwash, Thanks for reminding me... actually I do need to buy a pair or two of shoes before going on vacation Aug. 11...the problem with the rain is that it NEVER falls when I have no dances on the schedule and can enjoy the rain @ home, but ALWAYS when there's a dance...even when my decision is last-minute such as Friday afternoon [it stayed dry until I was already at the Dulles Hilton, then cut loose like crazy...though DCA apparently reported just 0.01"!] Anyway, Centreville and Chantilly as well as the Dulles Access Road/Toll Road/I-66 Corridor got PLENTY of rain Friday night...just wait till Tuesday evening, when I have a Clarendon Ballroom dance preceded by a 7 pm civic association meeting...and see what happens here in South Arlington--bet you won't need the hose around there!

I'm also noticing quite a bit of green grass and vegetation around here, thanks primarily to the good storms we got in the last week or two. [Most of those, BTW, came on dance nights.]

Posted by: Bombo47jea | July 18, 2010 1:50 PM | Report abuse

This has been a horrible year weatherwise. Since December, the weather has been awful. We had big storms in December, followed by massive storms in February. March was nice, but April, May, June and July have all been about 10 degrees too hot.

At this point, it will be October before we have decent weather if August and September continue the trend of average +10 temps.

Posted by: AxelDC | July 18, 2010 1:59 PM | Report abuse

Little cell popping up south of Bethesda and headed toward N DC area.

Posted by: Ian-CapitalWeatherGang | July 18, 2010 2:56 PM | Report abuse

Better hope the EURO model is wrong. Looks probably 90+ through the rest of the month. American longer range looks a little cooler next weekend.. maybe u 80s.

Posted by: Ian-CapitalWeatherGang | July 18, 2010 3:04 PM | Report abuse


Thanks for the comment. We try to cater to multiple audiences here. For example, if you're only interested in the nuts and bolts, we have a 6-day At-a-glance forecast from NWS at the top left of the page, and our own Express forecast within the forecast post. We do like to shoot the breeze a bit and inject personality into our detailed forecast narrative (not unlike some TVcasters have done for decades). Some people seem to like that about us. But don't feel obligated to scroll if you don't want to.

Posted by: CapitalWeatherGang | July 18, 2010 4:26 PM | Report abuse

AxelDC, your comment about waiting until October for (sustained) decent weather is pretty much spot-on, even for an average D.C. summer, much less a bad one like this. Summer, in this part of the country, often lingers through the first part of September (highs still average well into the 80s), and I think it was just two or three years ago (CWG Gang, help us out with the stats) where we had a 94 in early October.

Once October arrives, though, sometime during the month, we usually get at least one serious cold front, and that will start the fall leaf-change color.

On rare occasions (like the infamous fall/winter of 1976-77, where 30-degree minimums started in late September) cold weather will start early, but that is the exception rather than the rule. That BiCentennial fall/winter of 76-77 was something else, for those of you old enough to remember it. An incredibly large and deep East Coast trough and West Coast Ridge produced deep-freeze temperatures and even snow as far as south Florida and offshore into the Bahamas.

Posted by: MMCarhelp | July 18, 2010 4:38 PM | Report abuse

technorati complains too much. she has her head where it is always cloudy.

Posted by: axolotl | July 18, 2010 7:00 PM | Report abuse

@MMCarhelp, I do remember the 76-77 winter - I was visiting Annapolis for Christmas, and it was -7 there Christmas eve (while we were walking to services!). Then I went back to CT where I was living at the time, and had the fun of shovelling out a cul-de-sac when New Haven got dumped on somewhat later...

Posted by: fsd50 | July 18, 2010 9:07 PM | Report abuse

This just in: It's hot in Forest Glen.

Posted by: OMGPonies | July 18, 2010 9:50 PM | Report abuse

Thunder & lightning in Centreville VA, and a
strange feeling of deja vu.......

Posted by: FIREDRAGON47 | July 18, 2010 9:56 PM | Report abuse

Fairfax county; get your rain buckets ready.

Posted by: FIREDRAGON47 | July 18, 2010 10:14 PM | Report abuse

"Thunder & lightning in Centreville VA, and a strange feeling of deja vu......."

Oh no, I can see I'm going to be woken up at midnight by thunder and lightning again, here in Silver Spring.

Posted by: Murre | July 18, 2010 10:15 PM | Report abuse

I'm getting slammed in Fairfax right now with a giant thunderstorm. Heavy rain, thunder, lightning, the works. Deja vu indeed. This is happening nightly. So much for "isolated" thunderstorms. I'm right in the bulls-eye every night it seems.

Posted by: rwalker66 | July 18, 2010 10:30 PM | Report abuse

Pouring buckets most of the past half hour here in Herndon, though it sounds like the thunderstorm is now moving away east.

Posted by: fsd50 | July 18, 2010 10:43 PM | Report abuse

I hope there aren't any late Sunday night dances that will be affected by these storms. ;-)

Posted by: ana_b | July 18, 2010 10:43 PM | Report abuse

One little rumble of thunder and some light rain here in Ashburn, north of Rt 7.

Posted by: natsncats | July 18, 2010 10:49 PM | Report abuse

Raining a bit harder in Ashburn now. Yay!

Posted by: natsncats | July 18, 2010 10:59 PM | Report abuse

Plenty of lightning, thunder, and rain at Court House for the past 10 minutes or so. Excellent sleeping soundtrack!

Posted by: NoVAHoyaDan | July 18, 2010 11:01 PM | Report abuse

That thunder is louder than the last storm that woke me up!! I may go cower in the basement for the duration.

Posted by: Murre | July 18, 2010 11:02 PM | Report abuse

Damn! Thunder and lightning 30 mins ago just skirted to the north of us ... so tantalizing!

Posted by: weathergrrl | July 18, 2010 11:10 PM | Report abuse

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