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Old 03-29-2024, 08:42 AM
 
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This thread is to look at the number of tropical days experienced in different climates.

For this topic, a tropical day is one where the average temperature is at least 18°c

In Atlanta, our first tropical day of the calendar year was on January 25th, with an average temp of 18.4. The high was 22 low was 17 that day. There were a couple other 17° days in January, but we only had one tropical day

February did not have any tropical days at all. The closest we came was February 27th, where the average was 17.8°

Although we had a warm February for local standards (average temp of 11.6°, average highs was 17.2°), there were 0 tropical days that month.

March we have had 3 tropical days so far. The warmest one, on March 14th, we saw an average temp of 19.6°, min temperature of 17 and the high of 27.

We are expected to have at least one more tropical day on Sunday, and possibly one tomorrow. April 1st is expected to definitely be a tropical day, with even a minimum temperature of 19°

Atlanta Summary:
Jan: 1
Feb: 0
Mar: 3 (as of today)

YTD:4

This is an exciting time to monitor for this area, because we will typically start to see a huge increase of tropical days going into April. For example, last year we had 15 tropical days in April, although we also had 10 in March of 2023.

By the end of April and going into May, most days should be tropical days. By late may it is expected that every day will be tropical, and typically every day will be tropical through September.

In 2019, the average temperature was above 20c each day from May 16th until October 13th, so quite a good run. Some years there will be the odd non tropical day in September, but most days we are seeing 29 or 30 tropical days that month, and tropical days start to drop off substantially in mid October.

I am interested to hear about tropical day patterns and YTD numbers for other areas
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Old 03-29-2024, 09:46 AM
 
Location: Centre Wellington, ON
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We probably won't get any until May. Our last ones were in October.

Oct 2: 18.3C
Oct 3: 19.5C
Oct 4: 19.4C
Oct 5: 19.0C
Oct 27: 18.2C

Last spring, we managed to crack the tropical mark with the record breaking torch heat in mid-April, but only barely
Apr 13: 19.1C
Apr 15: 18.7C

Daily averages are only above 18C from Jun 23 to Aug 24 (1940-2023 normals).

First 18C mean last 20 years
2023: Apr 13 - 19.1C
2022: May 12 - 18.4C
2021: May 20 - 20.8C
2020: May 24 - 19.5C
2019: Jun 8 - 18.0C
2018: May 2 - 19.5C
2017: May 18 - 22.5C
2016: May 25 - 19.5C
2015: May 8 - 20.5C
2014: May 13 - 19.9C
2013: May 20 - 20.2C
2012: May 20 - 20.0C (came close, 17.3C, during the March 2012 heat wave)
2011: May 22 - 19.5C
2010: May 2 - 19.1C
2009: Apr 25 - 19.6C
2008: May 26 - 18.2C
2007: May 15 - 20.0C
2006: May 27 - 18.0C
2005: Jun 2 - 18.3C
2004: May 12 - 19.7C
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Old 03-29-2024, 09:48 AM
 
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I'm interested to compare Atlanta to Los Angeles. Both cities are at a similar latitude, although Los Angeles has a more gentle and less seasonal climate, known for good weather. There is also more dramatic microclimates in this area. For the comp I will use the Burbank Airport station, which is not going to be the most favorable station for them in the area. However it is a reasonable middle ground, being somewhat inland and somewhat elevated, although somewhat less elevated than Atlanta's airport station.

Although Burbank had an average January temp of 12.3, much warmer than Atlanta's January average of 6.6, it did not record any tropical days. Like Atlanta's February, it did come close at 17.3.

February again didn't have any tropical days, with the warmest day being 16.8

Even in March they did not have any tropical days, with the warmest day being only 16.4. This is despite the average day reaching 13.4 for the month!

Tropical Days for Los Angeles County (Burbank Airport)

January: 0
Feb:0
Mar:0

Last year, they recorded their first tropical day on April 10th and recorded a few more tropical days that month. Will be interesting to see when they record one for the first time in 2024.
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Old 03-29-2024, 09:59 AM
 
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Last one for now I will add is Charleston, SC.

Even though it is in SC, it is south of Atlanta by about a degree of latitude. It is also coastal, while Atlanta is hours inland and at a small elevation. These little factors give Charleston a huge advantage in tropical days. One would expect to see quite a few tropical days here in the winter and early spring.

Taking a look at 2024, they recorded their first tropical day on January 24th. One day earlier than Atlanta. However they did not cool off as quickly and ended up recording 4 tropical days in a row in late January, with the warmest day averaging a sweltering 21°C and even staying above a tropical 18 for the daily low.

In February, like in Atlanta, they had fewer tropical days. They still managed to get 2 that month and did not record any freezing temperatures in February.

March is where it really takes off, with Charleston recording a staggering 15 tropical days so far this month, and the potential for at least one more before the end of the month. Charleston is less than a degree away from having an actual tropical climate this March, with an average monthly temperature to-date of 17.22.

Charleston Totals:
Jan: 4
Feb:2
Mar:15 (to date)

Total: 21 (out of 89 possible days so far)
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Old 03-29-2024, 10:54 AM
 
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Quote:
Originally Posted by Space_League View Post
Last one for now I will add is Charleston, SC.

Even though it is in SC, it is south of Atlanta by about a degree of latitude. It is also coastal, while Atlanta is hours inland and at a small elevation. These little factors give Charleston a huge advantage in tropical days. One would expect to see quite a few tropical days here in the winter and early spring.

Taking a look at 2024, they recorded their first tropical day on January 24th. One day earlier than Atlanta. However they did not cool off as quickly and ended up recording 4 tropical days in a row in late January, with the warmest day averaging a sweltering 21°C and even staying above a tropical 18 for the daily low.

In February, like in Atlanta, they had fewer tropical days. They stll managed to get 2 that month and did not record any freezing temperatures in February.

March is where it really takes off, with Charleston recording a staggering 15 tropical days so far this month, and the potential for at least one more before the end of the month. Charleston is less than a degree away from having an actual tropical climate this March, with an average monthly temperature to-date of 17.22.

Charleston Totals:
Jan: 4
Feb:2
Mar:15 (to date)

Total: 21 (out of 89 possible days so far)
This is one thread I'm very interested in participating in to report on my Southeast US weather monitoring. You beat me to special spot Charleston Airport, but I'll be back for more places.

Just one thing though: going from your description, the site you are looking at is not coastal, it is inland about 10-15 km. You may have mixed up inland Charleston Airport with coastal Downtown Charleston.
For actual coastal Charleston, January had no tropical days (closest 17C on the 9th, 25th, and 26th), and February had only one (18C on the 28th). However, March is similar to the inland airport with 13 so far.

I am surprised at the low count of tropical days in January and February so far, it looks like even the lows on the warmest days were colder than the airport which is odd.

Sidenote: those tropical days at the inland airport were part of a period of very wild temperature swings from well above average to well below average and came mere days after the coldest days of the 2023-24 winter. Just like is par the course for the Southeast US.
Over the course of 10 days it went like this:

1/19: 18/3C (close to normal)
1/20: 7/-3C (below normal)
1/21: 7/-5C (coldest day of the season, mean of 1C)
1/22: 16/-5C (below normal)
1/23: 19/10C (above normal)
1/24: 25/17C (tropical)
1/25: 26/17C (tropical)
1/26: 28/17C (tropical, and tying the all time record high for the month)
1/27: 26/16C (tropical)
1/28: 21/10C (above normal)

Notice how in 3 days we go from an average Wichita January day to an average Florida Keys January day, and in 2 days there is a 22C increase in the lows.

Last edited by Can't think of username; 03-29-2024 at 11:02 AM..
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Old 03-31-2024, 05:31 PM
 
Location: White House, TN
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In Nashville, TN, the first tropical day of 2024 was February 26, with a high of 76 F / 24 C and low of 55 F / 13 C. The mean is thus approximately 65.5 F / 18.6 C.

February had 2 tropical days (26th, 27th), and March had 4 (4th, 14th, 30th, 31st).

In 2023, we had 4 in Feb, 4 in Mar, 7 in Apr, 26 in May, 30 in Jun, 31 in Jul, 31 in Aug, 30 in Sept, 14 in Oct, and 3 in Nov. Every day from May 5 - October 6 (excepting May 28) was tropical. There were a total of 180 tropical days in 2023.

In 2022, we had 4 in Mar, 9 in Apr, 29 in May, 30 in Jun, 31 in Jul, 31 in Aug, 27 in Sept, 11 in Oct, 7 in Nov and 1 in Dec. The longest streak was May 9 - September 27. There were a total of 181 tropical days in 2022.

First-last tropical days by year, and longest streak

2024: February 26 -
2023: February 15 - November 16 (Streak: May 29 - October 6)
2022: March 5 - January 3 (2023) (Streak: May 9 - September 27)
2021: February 28 - January 1 (2022)
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Old 03-31-2024, 05:42 PM
 
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Here's the current 2024 data for newly-crowned special spot Valdosta Airport. It is a special spot because it appears to be capable of the most wintertime heat of anywhere in Georgia.

January had 5 tropical days: 25/12C on January 7, 27/17C on January 24, 28/20C on January 25, 27/19C on January 26, and 29/19C (tying the all time record high for January) on January 27.

February had 6 tropical days: 25/11C on February 10, 26/14C on February 11, 23/17C on February 12, 26/10C on February 23, 27/11C on February 27, and 28/11C on February 28.

March had enough tropical days to be tropical, it averaged 25/12C for both the whole month and the winter (March 1-19) part.
Even in the winter part, the only non-tropical days were March 10-13 and March 18-19, which gives us a total of 18 tropical days for the month when we remove the non-tropical spring days of March 20, 21, 24-25, 29-31. In fact the hottest temperature of the month - a scorching 32C - happened in the winter part (March 15).
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Old 03-31-2024, 09:31 PM
 
Location: White House, TN
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Found something I didn't like about my climate.

We have never had a non-tropical day in July. We have them in June, very rarely (last one was June 2, 2012) and we have them in August even more rarely - a grand total of 12 since 1875, and just 8 of those in living memory (i.e. since 1907, when the oldest living person was born), with the most recent being on August 13, 2004.
But not one in July. NOT. ONE.

Just give us like, one cold day in July just so I can say it's happened.
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Old 03-31-2024, 10:14 PM
 
Location: Centre Wellington, ON
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Quote:
Originally Posted by wawa1992 View Post
Found something I didn't like about my climate.

We have never had a non-tropical day in July. We have them in June, very rarely (last one was June 2, 2012) and we have them in August even more rarely - a grand total of 12 since 1875, and just 8 of those in living memory (i.e. since 1907, when the oldest living person was born), with the most recent being on August 13, 2004.
But not one in July. NOT. ONE.

Just give us like, one cold day in July just so I can say it's happened.
Yeah, the heat is much more unrelenting in southern US summers than here.

Last summer, in terms of non-tropical days, we had

19 in June
12 in July
20 in August

Coolest days in month last summer

June
63.1F/48.2F - June 13
July
69.3F/52.2F - July 13
August
60.6F/43.7F - August 30

Days with *highs* below 64.4F/18.0C last summer
3 in June
0 in July (coolest high was 69.3F)
3 in August
... but only 4 in September, and the coolest August day (60.6F) was cooler than the coolest September day (61.0F).
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Old 03-31-2024, 11:04 PM
 
Location: Northern Virginia
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Wasn't familiar with this terminology (where I'm from in Europe nights with a low above 20C are called 'tropical nights' but there's no term such as 'tropical day').



This year D.C. had one day with an average temp above 18C in January - 1/26 - and one in March - 3/15. Of course, in the summer D.C. typically sees long uninterrupted stretches of such days. In the last 40 years, D.C. had no non-tropical July days, 4 non-tropical August days and only 39 non-tropical days total between June 8th and September 12th.


It's interesting how those chances develop. Even into mid-April your chances hover in the 20% range, then they only slowly increase and by mid-May they reach 50%. But then they quickly increase and by early June you're in the 90+% range. It shows how unstable warm weather still is in the Mid-Atlantic until you get a couple weeks into May where it then quite rapidly in the course of two weeks goes from "a decent possibility" to "extremely likely". In the fall your odds remain 90+% into mid-September then slowly fall to around 75% by the end of September and reach 50% in the first week of October but only get to that 20% by the end of October. So late October is analogous to early April, which showcases seasonal lag quite nicely. If you wanted to define summer as the time with a 75%+ chance of a 'tropical day' then summer would last from May 24th until September 28th here.
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