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I grew up in the SE USA and I've also lived in 15 different countries in 4 continents as well as the western USA and I would rate the SE USA climate average. I prefer it over colder climates and perpetually hot and humid climates but not over Mediterranean climates or Arizona climates.
Others are might be more sensitive to sudden extreme freezes, especially if they occur while the plants aren't dormant. For example, some plants in the US South may not have been dormant in Oct 18-20 when the first freeze occurred in much of the region, since average daily highs are still around 21-27C at that time of year.
Can't comment on anything plant related but I'd just like to give a reminder to anyone who sees this and may not know that for the places in question, last year's October first frost was a freak event as rare as freak frosts in tropical South Florida.
Can't comment on anything plant related but I'd just like to give a reminder to anyone who sees this and may not know that for the places in question, last year's October first frost was a freak event as rare as freak frosts in tropical South Florida.
Presumably you knew that already, though.
It was a bit of a freak event yeah, but even if the "freak event" was happening in Toronto, Toronto would not be getting a freeze at a time of year when average daily highs are in the mid 20s, which is like mid-late August here. The earliest Downtown Toronto has ever had a freeze was September 22, all the way back in 1840... In the past two decades, the earliest freeze was October 18 at Downtown Toronto, that's a long way from mid August, in fact average daily highs in that part of October are only 13-14C.
Even somewhere that doesn't get as much lake and UHI moderation, like Hamilton Airport, the earliest freeze (1960-2022 records) was Sept 21, 1991, a date for which the average high is 19.7C.
The Christmas freeze was extreme too. Somewhere like Little Rock going from -17C to 23C a few days later just wouldn't happen in Southern Ontario. The difference between the record high and record low on most days when the average temperature is somewhere in the middle of that (ex early November or mid March) is only about 26-30C at a place like Hamilton Airport. So a 40C swing like that... I'm not saying it's impossible, but I'm not sure if it's ever happened. The latest Hamilton Airport saw 23C+ was November 10, 2020, and the earliest it saw <=-17C was December 2, 1976.
So to match what Little Rock pulled off, Hamilton Airport would have to have -17C two weeks earlier than it ever had before in 62 years of records AND hit 23C two weeks later than it even had before, on the same year.
Depends on the place too. Nashville is one of those climates that can get a lot cooler than one might expect. it looks like they hit 1c on that October cold front which is not that unusual for them.
2021 October was much warmer for them with 7 min temp in the month
2020 couple days with low of 4
2019: low of 3 on oct 13 and a low of 2 on halloween
2018: low of 1 on Oct22
2017: first freeze oct29 and low of -1 on oct30 (with a high of 22 in between!)
2016: low 5 on oct23
2015: low of 1 on oct 19(basically identical to 2022)
2014: low of 3 on oct 5 (just a few days after a run of 30+ highs)
2013: string of sub5 nights culminating in a first freeze on oct25 and a -2 low on oct26
So out of 10 years, 8 of them including 2022 Nashville managed to make through October without a freeze.
Of course there are other places in the SEUS that deviated a lot more from typical patterns during that time. One of the most extreme with Tallahassee first freeze on Oct20. Without checking I think I would have to go back a lot of years to see the last time they had something like that.
Depends on the place too. Nashville is one of those climates that can get a lot cooler than one might expect. it looks like they hit 1c on that October cold front which is not that unusual for them.
2021 October was much warmer for them with 7 min temp in the month
2020 couple days with low of 4
2019: low of 3 on oct 13 and a low of 2 on halloween
2018: low of 1 on Oct22
2017: first freeze oct29 and low of -1 on oct30 (with a high of 22 in between!)
2016: low 5 on oct23
2015: low of 1 on oct 19(basically identical to 2022)
2014: low of 3 on oct 5 (just a few days after a run of 30+ highs)
2013: string of sub5 nights culminating in a first freeze on oct25 and a -2 low on oct26
So out of 10 years, 8 of them including 2022 Nashville managed to make through October without a freeze.
Of course there are other places in the SEUS that deviated a lot more from typical patterns during that time. One of the most extreme with Tallahassee first freeze on Oct20. Without checking I think I would have to go back a lot of years to see the last time they had something like that.
Yeah, Nashville was an outlier in the US South in terms of surviving the Oct 18-20 freeze, along with Memphis, Tupelo and Little Rock. However, almost the entirety of OK, TN, MS, AR, AL, as well as large chunks of SC, GA and LA, and even East Texas and parts of North FL froze.
There were some outliers even further north than Nashville though. Eastern KY like Prestonburg and Jackson survived the freeze, as did Buffalo, Toronto, Pittsburgh, Detroit, Chicago and Milwaukee... and even Montreal, Burlington, VT, Traverse City, MI, Collingwood, ON and Goderich, ON. Cleveland not only survived the late October frost threats, but it also survived the November 12-13 freeze that took out the Southern US outliers (Nashville, Memphis, Little Rock, Tupelo, Eastern KY), lasting until November 17.
Pertinent to this thread, I think the Southeast has some great examples of 3 season climates when you start looking at the middle ground subtropical climates. Not a very often discussed type of seasonal climate for sure, I think because they are often just wrongly stereotyped into 'warmer 4 season climates' or something like that.
Quintessential subtropical Dallas for example has a mild winter as warm as the spring/fall of the quintessential 4 season Dfa/Dfb humid continental climate, a warm-hot spring/fall as warm as the summer of said humid continental climate, and a quite hot summer as hot as or hotter than year round tropical weather.
For the purposes of those from 4 season climates, the seasons are essentially tropical+ summer, humid continental summer, and humid continental spring/fall. Anywhere in the Southeast with a coldest month of close to 9C would fill the bill, and it's probably the kind of people who like lots of heat but also want a moderate cooldown (to mild instead of cold weather).
It depends how you define seasons. If you use a middle of the road humid continental climate as the baseline, then yes, Dallas winters are comparable to the humid continental spring/fall, with the coldest winter temperatures in Dallas being similar to the coldest November/March temperatures a typical humid continental climate would achieve.
From an ecological point of view, I would say it's not really a 4 seasons although sometimes it almost feels like it.
Depends on the place too. Nashville is one of those climates that can get a lot cooler than one might expect. it looks like they hit 1c on that October cold front which is not that unusual for them.
2021 October was much warmer for them with 7 min temp in the month
2020 couple days with low of 4
2019: low of 3 on oct 13 and a low of 2 on halloween
2018: low of 1 on Oct22
2017: first freeze oct29 and low of -1 on oct30 (with a high of 22 in between!)
2016: low 5 on oct23
2015: low of 1 on oct 19(basically identical to 2022)
2014: low of 3 on oct 5 (just a few days after a run of 30+ highs)
2013: string of sub5 nights culminating in a first freeze on oct25 and a -2 low on oct26
So out of 10 years, 8 of them including 2022 Nashville managed to make through October without a freeze.
Some good points made there. I agree with the premise of getting a lot cooler than one might expect (certainly bucked my expectations when I was getting back into climatology), but as far as negative deviation is concerned, there is remarkably little, probably related to the urban heat island.
You'd expect with a normal 0.7C minimum that October first frosts would not be that uncommon, quite the contrary to what you noted that only 2 out of 10 had happened. I would expect somewhere like Birmingham Alabama to be more like that, and I guess it's also why Nashville and Tallahassee airports literally have the same all time record lows for May.
Quote:
Originally Posted by Space_League
Of course there are other places in the SEUS that deviated a lot more from typical patterns during that time. One of the most extreme with Tallahassee first freeze on Oct20. Without checking I think I would have to go back a lot of years to see the last time they had something like that.
Yeah, the Tallahassee airport is one of the exact places I had in mind, the reason it deviated so much is because it's literally a rural low elevation cold hole with sandy soil in a radiational frost unlike urban Nashville.
Just checked the data and it turns out October frosts there are almost TWICE as rare as frosts in say West Palm Beach, so my as rare as statement was actually a serious understatement. That was actually their second earliest frost ever, only other time that was earlier was October 18 1977 and only October 21 1989 got close after that.
Conversely FSU Tallahassee would be Tallahassee's equivalent to Nashville. Tallahassee is definitely no Nashville for urban heat island but FSU Tallahassee makes up for that with an elevation 2 1/2 times that of the cold hole airport, which gives enough cold air drainage for the city to be warmer relative to the airport than Nashville is relative to its suburbs despite the weaker urban heat island.
They didn't even get to 5C during the freak October cold snap, and I think the low they did record was the coldest they got in October since the station was set up in June 2014.
I think if records went back as far as the main airport it would never have had an October frost, all the October freak frosts at the cold hole airport seem to be radiational and the high elevation gives perfect protection against that. Too bad there's no data at FSU for October 2008 to see how it compared to the airport's all time October record low though, would be very interesting.
Last edited by Can't think of username; 01-03-2023 at 05:57 PM..
It was a bit of a freak event yeah, but even if the "freak event" was happening in Toronto, Toronto would not be getting a freeze at a time of year when average daily highs are in the mid 20s, which is like mid-late August here. The earliest Downtown Toronto has ever had a freeze was September 22, all the way back in 1840... In the past two decades, the earliest freeze was October 18 at Downtown Toronto, that's a long way from mid August, in fact average daily highs in that part of October are only 13-14C.
Even somewhere that doesn't get as much lake and UHI moderation, like Hamilton Airport, the earliest freeze (1960-2022 records) was Sept 21, 1991, a date for which the average high is 19.7C.
I think the reason why Ontario doesn't get freak frosts in the same way the Southeast US gets freak frosts is because of the soil composition. As I believe you told me in the 2022 first frost thread a while back, Southern Ontario does not have the sandy soil like say Archbold Biological Station, while the Southeast US is LOADED with sandy soil because of the sandy coastal plain covering so much of it, so way more risk of radiational cooling relative to the averages outside elevated areas/coastal areas/urban heat islands.
Quote:
Originally Posted by memph
The Christmas freeze was extreme too. Somewhere like Little Rock going from -17C to 23C a few days later just wouldn't happen in Southern Ontario. The difference between the record high and record low on most days when the average temperature is somewhere in the middle of that (ex early November or mid March) is only about 26-30C at a place like Hamilton Airport. So a 40C swing like that... I'm not saying it's impossible, but I'm not sure if it's ever happened. The latest Hamilton Airport saw 23C+ was November 10, 2020, and the earliest it saw <=-17C was December 2, 1976.
So to match what Little Rock pulled off, Hamilton Airport would have to have -17C two weeks earlier than it ever had before in 62 years of records AND hit 23C two weeks later than it even had before, on the same year.
Probably has to do with the Southeast US' much greater capability to warm up. The cold goes away much faster and is replaced with much greater warmth, leading to greater overall swings.
Yeah, Nashville was an outlier in the US South in terms of surviving the Oct 18-20 freeze, along with Memphis, Tupelo and Little Rock. However, almost the entirety of OK, TN, MS, AR, AL, as well as large chunks of SC, GA and LA, and even East Texas and parts of North FL froze.
There were some outliers even further north than Nashville though. Eastern KY like Prestonburg and Jackson survived the freeze, as did Buffalo, Toronto, Pittsburgh, Detroit, Chicago and Milwaukee... and even Montreal, Burlington, VT, Traverse City, MI, Collingwood, ON and Goderich, ON. Cleveland not only survived the late October frost threats, but it also survived the November 12-13 freeze that took out the Southern US outliers (Nashville, Memphis, Little Rock, Tupelo, Eastern KY), lasting until November 17.
I think it mostly had to do with the radiational nature of the frost (sandy soil places way more vulnerable) as well as different amounts of urban heat island at each station and the jet stream positioning itself upwards further east (which is why Gander got its second latest first frost ever while Tallahassee airport got the second earliest first frost ever).
In particular none of the places that got past it are especially vulnerable to radiational cooling, not even Tupelo for some reason (moderate diurnal range and record lows relative to more radiation vulnerable places).
It depends how you define seasons. If you use a middle of the road humid continental climate as the baseline, then yes, Dallas winters are comparable to the humid continental spring/fall, with the coldest winter temperatures in Dallas being similar to the coldest November/March temperatures a typical humid continental climate would achieve.
What I was defining 'seasons' as is the kind of temperatures the quintessential Dfa/Dfb humid continental climate gets, sorry if that wasn't clear. Oshawa is the one I had in mind, as a Dfb that is close to Dfa it fills the bill nicely. https://en.wikipedia.org/wiki/Oshawa#Climate
As for what the coldest temperatures Dallas normally gets in winter are comparable to, that's not quite the case with Oshawa. I've been in Oshawa during April cold spells more times than I can count and Dallas Love Field's median coldest winter temperature of -6.7C is pretty comparable to what I remember experiencing when I was there at the time (between -4 to -8C), so I would say Dallas' coldest winter temperatures are more in line with what the spring/fall of a middle ground humid continental climate sees as its coldest temperatures.
A cooler 1/3 subtropical climate like Tulsa would be more in line with having its usual coldest winter temperatures on par with the usual coldest November/March temperatures of a humid continental climate middle ground, I have experienced plenty of March cold and some November cold in Oshawa that was right around what Tulsa would get for the coldest of the season.
Quote:
Originally Posted by memph
From an ecological point of view, I would say it's not really a 4 seasons although sometimes it almost feels like it.
Given my lack of knowledge on ecology I'll take your word for most of this, but February 2021 streetviews are not to be gone off of for obvious reasons. I would look for a February 2018 or 2020 streetview, unlike 2021 those Februaries were fairly normal.
Quote:
Originally Posted by memph
I suspect a bit further north like Tulsa, OK you would have more of a "hard dormancy" period in Dec-Feb.
That sounds about right. Barring the warm spells, Tulsa's December-February is pretty much identical to the weather in Oshawa when the dormancy begins in fall/is in its last in spring.
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. I agree with the premise of getting a lot cooler than one might expect (certainly bucked my expectations when I was getting back into climatology), but as far as negative deviation is concerned, there is remarkably little, probably related to the urban heat island.
. That was actually their second earliest frost ever, only other time that was earlier was October 18 1977 and only October 21 1989 got close after that.
