How hot was it?

– Posted in: Weather

Talitha forwarded to me this excerpt from an email she had written to a friend concerning our abnormally hot weather. She had gone to the trouble of compiling our handwritten notations of maximum and minimum temperature, which Cadie writes down in my Lee Valley Gardening Journal.

“Apparently, we got our ‘normal’ summer weather in April and May. We hit our first 90 degree day on May 11. Mostly for my own amusement (though you should feel free to feel amused as well), here is some pointless data entry. Starting with June 1, our weather looks like this (I’ll highlight interesting points):

Day Max Min Notes
01 88.6 44.8
02 91.6 50.2 jump of about 50 degrees in 12 hours followed by a 40 degree drop.
03 84.8 51.1
04 89.8 56.7
05 93.4 53.3
06 93.4 58.1
07 91.6 54
08 99.4 53.8
09 94.9 63.2

—skip three days (unrecorded)—

13 97 assuming the unrecorded days were all in the 90s as well (and I think they were) this is a 9 day run of 90 degree weather

14 88.9 69.5
15 84.1 65.3
16 71.3 56.7
17 71.5 48.6
18 65.7 55.4
19 75.1 50.6
20 89.3 49.5
21 89.3 50
22 82.3 54.5
23 86.4 38.5 lowest temp in June
24 92.7 48.2 50 degree jump in 12 hours
25 98.3 52.6 And then drop 40 degrees, and then climb 50 degrees. . .
26 99.4 61.4 And then drop 50 degrees, and then climb 50 degrees. . .
27 99.4 59.6
28 96.1 65
29 94.9 67.9
30 94.1 67.5


01 94.1 61.0 End of eight day run of 90 degrees
02 81.2 53.5
03 86.4 42.7 coldest day in July so far.
04 92.7 54 50 degree jump in twelve hours
05 88.2 63.9
06 86.8 67
07 79.2 65
08 73.0 62.8
09 78.1 60.5 (July 9th, butchering day)
10 91.6 53.5
11 94.1 52.6
12 99.9 64.3 Hottest day of the year so far
13 92.7 65
14 91.6 62.3
15 97.0 61.7
16 91.1 69.5
17 92.7 71.5
18 97.0 71.5
19 96.1 68.2
20 91.6 59.6

  • An eleven day run of 90 degree weather (the 20th was the 13th day of 90 weather for July)
  • 36 days of 88 or higher weather
  • 15 days of 87 or lower weather (give or take 3 days) and about half of those nights were 57 or cooler.

I italicized the nights at 57 or cooler, because some plants are sensitive to weather cooler than 60 degrees. One book I read said not to plant out basil until the weather stayed about 60 degrees. If one interpreted this to mean the daytime weather, then I did that. If this means the night weather, then I shouldn’t be able to grow basil (but I am). Another book stated quite firmly that an eggplant will sustain damage in any weather below 60 degrees. I’m not growing eggplants, but I hear most people group together peppers and eggplants and both being very picky. So I wonder if that is one of the reasons why my peppers are always stunted and hardly produce a thing?

Personally, I like the cool nights. But maybe the plants don’t? Maybe I’ll have to try row covers?

Although we have been getting more rain than true ‘drought’ years, I keep thinking of it as a drought year because it is so hot everything evaporates off very quickly. The humidity has also been horrible this year. Needless to say, we usually just hide in the house during the afternoons.”

Now you know to the tenth of a degree how hot it’s been here. Or, rather, you know what temperature our weather sensor has recorded. One thing that has bothered me throughout this heat wave is that the National Weather Service has not been recording such high temperatures as we have. That would mean the rest of the county has been ignorant of our suffering, just as they remain oblivious to our late frosts and freezes. For example, yesterday (July 20th) they said the maximum was 82 degrees, and we registered 91.6 degrees on our outdoor sensor. That’s approximately a ten degree difference. Of course, we are on the eastern end of the county and they are on the western end. Is it really possible there could be that much difference between the two locations?

To try to get an idea if that were possible, I checked out an amateur weather site where the readings are taken from the same end of the county as our location. Hmm. His readings were higher than the NWS, but not by much: 83.2 degrees. Which brings me to my second possibility: what if our readings are off, and we are moaning and groaning about temperatures that are ten degrees lower than we think they are? How mortifying! Even worse, what if it feels hotter to us because we think it’s hotter? How pitiful!

So I emailed Jon, the owner of the Binghamton Weather. I told him, “I have the outdoor wireless sensor on the east side of the house where it is under the roof of what we call the patio but I think was used by the former owners as a carport. I don’t think the sun reaches it at all, perhaps just a bit in the early morning. But it is paved with concrete. Do you think the concrete is distorting the temperature readings? Or is it just hotter here?”

And he responded:
“It is possible that there are three factors affecting your readings:
1) Your sensor is on the east side of the house. It is recommended that the temperature sensor be placed on the north side. It is the side that receives the least amount of solar radiation and it is what is recommended by the National Weather Service.
2) The roof in the carport. It is generally not a good idea to have it under roof. Especially if it is a roof over a semi-enclosed area such as a carport, because if the sun is hitting that roof for a good part of the day it will be warmer directly under that roof.
3) The concrete pavement. It is generally recommended to mount the sensors as far away from a paved or concrete surface as practical.
The general rule of thumb is that the sensor be placed over a grassy area approximately 6 feet or more above the ground in a shelter or in a radiation shield in an open area. A radiation shield or instrument shelter is available from most weather instrument retailers such as Ben Meadows.”

So the short answer is, yeah, the location of the sensor is distorting the readings. In my defense, the instructions that came with my unit said the north side was preferable, but emphasized keeping it out of direct rain. The covered patio facing east was the only place I could put it that would be out of direct rain and still close enough to the receiving unit to maintain a consistent signal. And it’s completely open on three sides. I had never heard of Ben Meadows before, and it looks like it has a lot of interesting stuff. But those instrument shelters look far more enclosed than our former-carport-turned-patio (which is more of a bike garage than anything else, that is, unless it’s being used to raise chicks).

So how hot was it? That depends on whose sensor you want to believe. In the meantime, while the temperatures are still high, starting yesterday the humidity has dropped quite a bit, and the difference in how these temperatures are perceived has been dramatic. I feel like I’ve been released from captivity, delivered from oppression–and I even dared to use the oven last night. I even needed to pull a blanket over myself before morning! Yes, that’s good: one blanket with the window open. When you have five blankets on with the windows shut, and you decide you’d be a bit more comfortable with a hat on: that’s bad, but in a drafty old house owned by penny-pinchers, it can get that bad. And I’d take that over sweltering heat and humidity any day. That’s one of the reasons I live here.

About the Author

Kathy Purdy is a colchicum evangelist, converting unsuspecting gardeners into colchicophiles. She would be delighted to speak to your group about colchicums or other gardening topics. Kathy’s been writing since 4th grade, gardening since high school, and blogging since 2002.

In the end, this may be the most important thing about frost: Frost slows us down. In spring, it tempers our eagerness. In fall, it brings closure and rest. In our gotta-go world–where every nanosecond seems to count–slowness can be a great gift. So rather than see Jack Frost as an adversary, you could choose to greet him as a friend.

~Philip Harnden in A Gardener’s Guide to Frost: Outwit the Weather and Extend the Spring and Fall Seasons

Comments on this entry are closed.

bill July 22, 2005, 9:27 pm

perhaps you could get some corroborating data or even subjective opinions from other inhabitants of your valley.

actually we have our thermometer on the south side of the house but under the shade of a tree. ours is not wireless so it has a wire through a window about five feet above the ground. it is usually a little cooler than than what is reported, which I feel is probably right because we have so many trees.

Talitha July 21, 2005, 2:25 pm

Yeah, but I take issue. The very aluminum roof that is supposed to be trapping heat is shading it from the sun’s rays, and we all know you’re supposed to keep the sun’s rays. If it’s true that our concrete pad (which is so covered in stuff it isn’t funny, not to mention shaded by said roof) is radiating extra heat, it should also be making the low temperature higher than it ought to be, yes? If it is distorting it 10 degrees higher at the peak of the heat, oughten it also be about 10 higher at the cool of the morning? That would mean that on July 3 our “real” temperature would have been 32.7, or something close to that–at any rate, cold enough for frost to form on our unprotected car windsheilds, which did not happen. (Last year, however, Teman did scrape frost of his windshield on June 30th, so it’s not like it can’t happen. It just didn’t.)

I hold that (1) our thermometer is reasonably acurrate. Perhaps not to the tenth of a degree, but give or take only few degrees, not ten. And (2), that your average gardener, citizen, blog-reader, anyone-besides-a-certified-modern-weather-recorder doesn’t put their thermometer in a “grassy area approximately 6 feet or more above the ground in a shelter or in a radiation shield in an open area”. If we use that rule of thumb to throw out our data, we should probably chuck a lot of the older data the weather center has as well. Our data may not be perfectly scientific according to today’s modern standards, but I think it’s still perfectly usuable for general plant stress (too hot or too cold), and griping (c’mon, how many of you guys in TX have your thermometer in perfect conditions?).

Besides, I don’t think that we have to find fault with our data just because it’s different. Everyone knows about cold spots, even micro-climates where they can nurse along precious plants that are out of thier “proper” zone. In fact, compared to the Binghamton weather, we are a cold spot, getting our frosts earlier and often times much colder (even with said thermometer in the “wrong” place). I think our valley is just uniquely posistioned to extreme weather.

And finally, I don’t get what the big deal is. Human’s don’t stand around on grassy plains on the north side of buildings with radiation sheilds around them–so why should our thermometers? I certainly don’t even get to garden in the shade.