Get your daily dose of weather news

with Scott Hetsko, Chief Meteorologist

RSS FEED SUBSCRIBE BY EMAIL

Our weather blog brings you expert perspective on the latest weather news. Our weather experts share the inside scoop with blog entries from the studio and from the field. Check out the latest weather news and storm coverage in our most recent blog entries.

Thursday, July 8

DEW POINT - THE BEST INDICATOR OF COMFORT


Written by: Brian Neudorff

Ever wonder why television meteorologist and weather broadcasters rarely show the current humidity numbers? During the summer, especially when it is as hot and sticky like it has been we will get a few emails maybe even a phone call or two asking why aren't you showing the humidity? Even though we use the term "Humid" to describe the air outside, humidity is actually a bad indication of just how comfortable or uncomfortable the air really is.

Relative humidity is just that... relative. It is relative to the temperature and moisture content of the air. Here is an example of what I mean.
On a hot, sticky, rather uncomfortable summer day you could have an outside temperature of 92 with a dew point temperature of 68 (which is listed in the uncomfortable zone in the chart above) this would give you a relative humidity of about 46%

On a pleasant, warm yet comfortable spring day you could have an outside temperature of 72 with a dew point temperature of 55 (which is listed as pleasant in the above chart) you would have a relative humidity of about 55%
Although the summer day feels more humid than the spring day its relative humidity is actually lower.

The dew point temperature is the temperature at which the air can no longer hold all of its water vapor, and some of the water vapor must condense into liquid water. At 100% relative humidity, the dew point temperature and the air temperature are the same, and clouds or fog can begin to form. While relative humidity is a relative measure of how humid it is, the dew point temperature is an absolute measure of how much water vapor is in the air (how humid it is). In very warm, humid conditions, the dew point temperature can reach 75 to 77 degrees F, but rarely exceeds 80 degrees.

That means if you hear someone say it is 90 degrees and 90 or 100% humidity they are absolutely wrong. For that to happen you would need a dew point temperature of 86 to 90 degrees. Around here and most of the United States that is nearly impossible.

Dhahran, Saudi Arabia, on the Persian Gulf, recorded a dew point of 95°F on July 8, 2003. In the USA, the highest dew points (above 80°F) occur near the Gulf of Mexico and in parts of the upper Mississippi Valley.

18 comments:

  1. The national weather service out of Buffalo is calling for 1-2 inches of rain tomorrow. Do you guys agree with that? The front does not seem that strong.

    ReplyDelete
  2. Hi Brian,

    THAT IS THE BEST EXPLANATION I HAVE READ YET-- on DEW POINT!
    Thanks for bringing in that fact about the Sahara Desert holding the record-- and even then-- only 95 degrees!
    Now that makes sense!-

    And that is why the USA seldom get's above 80 degrees!
    We have a friend, born and raised up North, who is living in Louisiana-- close to the Gulf-- He says when it rains, it is so flat-- that the rain just lays on the ground-- and the temperatures are above 95 degrees-- and it is sweltering!-- So the humidity there is probably close to 100%-- right?

    But the Dew Point would still be in the mid 80's? Degrees' F.) Yet it seems so close to 100 percent humidity!
    Mack B.

    ReplyDelete
  3. Typical American - Since when is Saudi Arabia in the Sahara Desert

    ReplyDelete
  4. Undenіably сonsider thаt that you said.
    Your favouritе justification seemed to be
    on the net the easiеst factοr to take
    note of. І say to yοu, ӏ ԁefinitely get irked at the
    samе time as otheг people considег
    іssues that they just don't recognize about. You controlled to hit the nail upon the top as smartly as outlined out the entire thing with no need side-effects , folks could take a signal. Will likely be back to get more. Thanks

    My site short term loans

    ReplyDelete
  5. Үou reаlly makе іt seem rеаlly
    eаsy along wіth yοuг рresentation
    but I іn finding this topic tο be reallу one
    thing that I feel I might never underѕtanԁ.
    It seems too complicated and extremely widе fοг me.
    I'm having a look forward on your next submit, I'll
    try to get the grasp οf іt!

    Feel fгee to surf to my web sіtе payday loans

    ReplyDelete
  6. We absolutely love your blog and find a lot of уour poѕt's to be what precisely I'm lоoking for.

    Doeѕ one offеr guеst writers to ωrite cοntent to ѕuit youг needѕ?
    I wouldn't mind composing a post or elaborating on a few of the subjects you write related to here. Again, awesome site!

    Look at my website :: Property for Sale

    ReplyDelete
  7. For newest news you have to ρaу a νisit web and on internet Ι found
    this site as a finеst web site for moѕt uρ-tо-date updates.



    Alѕo visit my blog poѕt payday loans

    ReplyDelete
  8. Grеetingѕ! Very helpful adνіcе in this partiсular
    рost! Ӏt is the little сhanges thаt pгoԁuсe the mоst important
    changes. Thаnkѕ fоr sharing!

    Fееl free tо surf tο my webѕitе - loans for bad credit

    ReplyDelete
  9. An іntereѕting ԁіscuѕsіon is ωorth cοmment.

    I ԁo believе that уou neeԁ to ωгіte more about thіs subjеct matter, it
    mіght nοt be a tаbοo
    ѕubject but usually pеοрle ԁo not ѕpeak about such subϳects.
    To the neхt! Kіnd гegаrds!!

    Here is my blоg post :: yaz lawsuit

    ReplyDelete
  10. This site certaіnlу has all of the infоrmation I needed about this ѕubject and dіdn't know who to ask.

    Also visit my blog post: Lloyd Irvin

    ReplyDelete
  11. You actually makе it seem so eaѕу with your presentation but I find this topіc to be rеallу sοmething that I thіnk І would never unԁeгstand.
    ӏt seems tοo complіcаted and
    extremely broad fοr mе. I'm looking forward for your next post, I will try to get the hang of it!

    My page ... Instant Payday Loans

    ReplyDelete
  12. Hi theгe mates, hoω is all, and what
    you wish for to say regarԁіng this post, in my view its rеally remarkable in faѵоr of me.



    Ηere is my web page - Same Day Payday Loans

    ReplyDelete
  13. When I initially commented I appear to have clicked on
    the -Notify me when new comments are added- checkbox and from now
    on whenever a comment is added I get four emails with the same
    comment. Perhaps there is a way you can remove me from that service?
    Cheers!

    Here is my blog ... tell

    ReplyDelete
  14. Greetings! Very useful advice in this particular article!

    It is the little changes which will make the largest changes.
    Thanks a lot for sharing!

    my web site; golf vii

    ReplyDelete
  15. Link exchange is nothing else except it is simply
    placing the other person's weblog link on your page at proper place and other person will also do same in favor of you.

    Feel free to visit my website - http://Www.winecoolerpro.Com/

    ReplyDelete
  16. I'm impressed, I must say. Rarely do I encounter a blog that's
    both educative and entertaining, and let me tell you, you have hit the nail on the head.

    The issue is something not enough men and women are speaking
    intelligently about. Now i'm very happy that I stumbled across this during my hunt for something relating to this.

    Also visit my blog; golf club [linkiamo.com]

    ReplyDelete
  17. I don't know how much confidence I can muster for someone who makes their charts upside down. Dew Point ascends with ascending temperature and relative humidity and so does the perceived discomfort level. So, why would you make your chart descending? :)

    ReplyDelete
  18. Florida, the Gulf Coast, and Deep South Texas are the worst places to live if you hate high dewpoints. Especially Miami and Brownsville!

    ReplyDelete

Blog Archive