Monday, August 8, 2011

90 degrees vs. 98 ... a big difference

A weak cold front is forecast to cross the Charlotte area at midweek, and it'll drop our daily high temperatures into the range of 90 to 92 degrees.

Some of you might be saying that's not a big deal, but I think it is.

There's a big difference between 90 degrees and 98 degrees.

I've heard a lot of complaints about the heat this summer, and it didn't make a lot of sense at first, because we've only had two days of 100 degrees or higher, and that's certainly no record.

The number of 90-degree days is a bit above average, but we don't seem to be headed toward the record of 88, set in 1954.

But I might have found the answer when I went looking at the exact nature of the 90-degree days we've had so far this year. We've had a lot of days when it was 95 or hotter -- more than any year in the last decade, except last year.

An air conditioning mechanic told me last year that heating and air conditioning systems are built to work efficiently to certain temperature limits. He said it's the same story with the way houses are insulated. I forget what he told me about the heating systems, but I remember him saying that when temperatures got above the mid 90s, a lot of systems simply can't cool a house very well.

So here's the total for the past decade (through Aug. 7 each year):

2011: 20 days

2010: 24

2009: 2

2008: 14

2007: 5 (although there were 16 days of 95 or hotter after Aug. 7 that year, including six 100-degree days; August was nightmarish).

2006: 15

2005: 4

2004: 0

2003: 0

2002: 9


Anonymous said...

Sooo...other than 8 degrees, what's the difference between 98 and 90? Just that our A/C's can run more efficiently and thus we can stay cooler inside while Duke Energy laughs all the way to the bank? Is A/C efficiency the point of your post?

tarhoosier said...

The number of 90 degree days is on pace with last year which was second (by one) to the most ever. "a bit above average" is understating the issue significantly.

I Work Outside said...

To the first commenter......Let me tell you from someone who works outside, 8 degrees makes a HUGE difference when we are talking 90's. It may not mean much to you and your spinning chair, but come outside 5 days a week and you will have a different opinion.

You are dead on Steve.

Anonymous said...

tarhoosier......Do you know what the average number of days above 90 is? For the last 45 years the average is 38 days at or above 90 degrees. So yes, at this point in the year we are just above normal.

Anonymous said...

Global Cooling!!

Anonymous said...

I wonder if Texans still doubt science.

Anonymous said...

There might be a difference the way your A/C or insulation works, but each degree is still mathematically the same. Therefore, it is that big of difference between 70 and 78? Nope. Likewise, 90 and 98 are both hot, but 98 is not magically more hotter than the degrees it represents.

Warthog said...

Quantitatively sure, but not qualitatively. Big difference between water at 31 degrees and at 33 even though it's only 2 degrees.

Anonymous said...

It has been hot and humid here. Really it's been the humidity that makes the temps here seem hot. Get over it, we'll live...and sweat too.

Anonymous said...

Steve what are you talking about? 58 days at 90+ so far this year. 53 at this point last year. And we only barely missed the record last year. How can you write "we don't seem to be headed toward the record of 88"?

Do you know something we don't?

Anonymous said...


Anonymous said...

# of days with 95+ temp and 72+ average dewpoint:
2002: 1
2005: 4
2006: 4
2010: 6
2011: 8 so far, including yesterday

Anonymous said...

lol, you think it's been hot in NC. Try having week after week of 100 and above temps. North Carolinians are wimps, complain about weather and try to make it look like they know about football when in fact they are the laughing stock of the NFL

Anonymous said...

Try living in Joplin, MO where an EF5 tornado destroyed 1/3 of that city and now it's been baking, sizzling, or frying under 2weeks of CONSECUTIVE 100+ degrees days under sunny skies too.

Anonymous said...

Anonymous @ 12:01.............58 days of 90+ degree days??? Do the math on that. That would be 27% of the year thus far. There is no way that is accurate. That would mean the entire months of June and July were abouve 90. I know for a fact that's not right. I remember a week in July temps were in the 70's and 80's.

Anonymous said...

I know for a fact you are wrong.

Count for yourself:

And then apologize to me!

Anonymous said...

Anon 2:15 - I thought that was high, too, but it's true.

# of days of 90+ degree heat in Charlotte:

May: 6 days
June: 20 days
July: 25 days
August: 7 days

Ray said...

It's not the temp, it's the dew point that has been SO DARN HIGH this summer. Dew points in the high 70's just make it MISERABLE to do anything outdoors. It hurts to breathe outside.