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Old 04-01-2024, 09:03 AM
 
Location: Centre Wellington, ON
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Quote:
Originally Posted by Veritas Vincit View Post
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.
I would say that 30C+ days and 20C+ nights are more typical of tropical weather. The average day in a tropical rainforest climate might be a high of 32C and low of 23C.

The cut-off of 18C mostly comes into play in cases of sub-equatorial tropical climates like Stuart FL, Easter Island, Minamidaitojima Japan, Santos Brazil, Fort Dauphin Madagascar and Bermuda, as well as tropical highland climates like Popayan Colombia, Butembo DRC, Baguio Philippines, Kabanjahe Indonesia, Enarolati Indonesia and Kundiawa Papua New Guinea.
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Old 04-04-2024, 10:39 PM
 
Location: White House, TN
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On average (using 1991-2020), in Nashville, TN, we have:

3 days in March
11 days in April
23 days in May

for a total of 37 tropical days in spring.

During this period:
March's total has ranged from 0 to 15 - 1994, 1996, 1999, 2001, 2005, 2010, 2014 w/0 to 2012 w/15.
April's total has ranged from 2 to 19 - 2 in 1997 to 19 in 2017.
May's total has ranged from 12 to 30 - 12 in 1997 to 30 in 2018.

Not surprisingly, spring 1997 had the fewest such days, with 15. 2012 had 56, making the most.

On a yearly basis, we average 170 tropical days. 1997 had the fewest, with 147, and 2016 the most, with 193.

The longest streak of tropical days was 157, from May 6 - October 11, 2018. Interestingly, after that 2018 only had one tropical day (October 31).

The longest a year waited for its first tropical day was 2005, with April 5. The earliest last tropical day of any year was in 1997, on October 13.

Every month had some potential for tropical days, though some winters did not have any. The latest non-tropical day was June 22 (1992) and the earliest was August 13 (2004). August 13, 2004 was the sole non-tropical day in August in the entire 30-year normals period. There were only 3 non-tropical days between June 8 and September 4, inclusive.

January averaged 0 days
February averaged 1 day
March averaged 3 days
April averaged 11 days
May averaged 23 days
June averaged 30 days
July averaged 31 days
August averaged 31 days
September averaged 27 days
October averaged 12 days
November averaged 2 days
December averaged 1 day

See under the spoiler for more details.
Spoiler

List of tropical winter days, 12/1/90 - 2/29/20:
Feb. 8, 1994
Feb. 23, 1996
Feb. 26, 1996
Dec. 11, 1996
Jan. 3, 1997
Feb. 20, 1997
Dec. 5, 1998
Dec. 6, 1998
Jan. 22, 1999
Jan. 3, 2000
Jan. 29, 2002
Jan. 30, 2002
Jan. 31, 2002
Jan. 3, 2004
Jan. 13, 2007
Jan. 14, 2007
Dec. 9, 2007
Feb. 5, 2008
Dec. 27, 2008
Feb. 27, 2011
Feb. 29, 2012
Dec. 3, 2012
Jan. 11, 2013
Jan. 12, 2013
Dec. 4, 2013
Dec. 21, 2013
Feb. 20, 2014
Dec. 13, 2015
Dec. 23, 2015
Dec. 26, 2015
Dec. 27, 2015
Feb. 20, 2016
Dec. 25, 2016
Dec. 26, 2016
Feb. 11, 2017
Feb. 24, 2017
Feb. 15, 2018
Feb. 19, 2018
Feb. 20, 2018
Feb. 23, 2018
Feb. 24, 2018
Feb. 5, 2019
Feb. 6, 2019

List of non-tropical summer days, 6/1/91 - 8/31/20:
June 21, 1992
June 22, 1992
June 1, 1993
June 5, 1993
June 1, 1997
June 5, 1997
June 6, 1997
June 7, 1998
June 1, 2001
June 3, 2001
June 1, 2003
June 2, 2003
June 4, 2003
Aug. 13, 2004
June 1, 2012
June 2, 2012
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Old 04-06-2024, 07:49 PM
 
Location: St. Louis Park, MN
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Interesting concept.

Here's the amount that I had last year for each month:

J 0
F 0
M 0
A 4
M 18
J 29
J 31
A 31
S 24
O 3
N 0
D 0
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Old 04-10-2024, 12:44 PM
 
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Atlanta ended up just missing a tropical day on March 30th at 17.75 degrees. They did hit the tropical cutoff on March 31st, however. We have had a few tropical days so far in April. Despite some cooler nights, we hit the warmest day of the year so far at 21.6 on April 2nd.

Atlanta Summary:
Jan: 1
Feb: 0
Mar: 4
Apr: 3 (as of 4/10)

Total: 8

Next week will be very exciting, as we are forecast to get a heatwave! If the forecast holds, later next week into the weekend will be very warm, with highs near or at 30 and lows close to 20 degrees. Should be a good run of tropical days.

Notably, April 20th is the first day of the spring where the historical average temp is tropical for Atlanta.
It's interesting to see what day this happens in other places.

Orlando: Feb 20th
Phoenix: March 9th
Houston: March 19th
New Orleans: March 19th
Tallahassee: April 2nd
Charleston: April 10th
Atlanta: April 20th
Washington, DC: May 6th
San Diego: May 7th
New York City, May 19th
Chicago: May 25th
Los Angeles: May 28th
Minneapolis: May 30th
Boston: June 5th
Bangor: June 18th
Seattle: June 30th
San Francisco: July 31st
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Old 04-10-2024, 02:31 PM
 
2,844 posts, read 1,440,730 times
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Quote:
Originally Posted by Space_League View Post
Atlanta ended up just missing a tropical day on March 30th at 17.75 degrees. They did hit the tropical cutoff on March 31st, however. We have had a few tropical days so far in April. Despite some cooler nights, we hit the warmest day of the year so far at 21.6 on April 2nd.

Atlanta Summary:
Jan: 1
Feb: 0
Mar: 4
Apr: 3 (as of 4/10)

Total: 8

Next week will be very exciting, as we are forecast to get a heatwave! If the forecast holds, later next week into the weekend will be very warm, with highs near or at 30 and lows close to 20 degrees. Should be a good run of tropical days.

Notably, April 20th is the first day of the spring where the historical average temp is tropical for Atlanta.
It's interesting to see what day this happens in other places.

Orlando: Feb 20th
Phoenix: March 9th
Houston: March 19th
New Orleans: March 19th
Tallahassee: April 2nd
Charleston: April 10th
Atlanta: April 20th
Washington, DC: May 6th
San Diego: May 7th
New York City, May 19th
Chicago: May 25th
Los Angeles: May 28th
Minneapolis: May 30th
Boston: June 5th
Bangor: June 18th
Seattle: June 30th
San Francisco: July 31st
Before I put more data for more places in here, I'd like to point something out. When getting away from the unrepresentative cold hole that is the Tallahassee Airport, the 1st average tropical day would undoubtedly be sooner than April 2.

We can't know for sure because the not-cold-hole Tallahassee stations for which there is easy access data only began in 2014 instead of 1991 like would be needed for normals, but I think it is plausible for parts of Tallahassee like the Challenger Learning Center to begin average tropical days like Houston and New Orleans (which is, as you listed, the last day of winter) because its discrepancies with the cold hole airport are comparable to the Houston/New Orleans discrepancy, suggesting a similar first tropical day.
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Old 04-17-2024, 01:02 PM
 
Location: White House, TN
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I decided to analyze the last 100 years of tropical days by using the NOWData website. You can do the same for your climate by clicking "Calendar day summaries", putting in the desired year range, the variable "Avg temp", the summary "Number of years", and for the threshold, "> 64", because 64.4 F is the cutoff and the averages will always be a whole number or a .5 (so 64.5 would be >64, but 64 wouldn't).

The years I used were 1924-2023, inclusive.

Not surprisingly, the frequency of tropical days increased dramatically over the course of the spring, from fewer than 5% during early March to near 90% during the last few days of May.

Between April 30 - October 7, a day was more likely than not to be tropical.
Attached Thumbnails
Spring Tropical Days Thread-tropical-days-day-year.png  

Last edited by wawa1992; 04-17-2024 at 01:27 PM..
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Old 04-28-2024, 09:16 PM
 
2,386 posts, read 1,874,552 times
Reputation: 2516
Quote:
Originally Posted by wawa1992 View Post
I decided to analyze the last 100 years of tropical days by using the NOWData website. You can do the same for your climate by clicking "Calendar day summaries", putting in the desired year range, the variable "Avg temp", the summary "Number of years", and for the threshold, "> 64", because 64.4 F is the cutoff and the averages will always be a whole number or a .5 (so 64.5 would be >64, but 64 wouldn't).

The years I used were 1924-2023, inclusive.

Not surprisingly, the frequency of tropical days increased dramatically over the course of the spring, from fewer than 5% during early March to near 90% during the last few days of May.

Between April 30 - October 7, a day was more likely than not to be tropical.
That is a great tool.

April 10th, last time I posted, was the 4th tropical day in April for Atlanta.

Now we are at 17 for April! The coldest day of the month hit a low of 5C and average temperature of 11.6

The temperature has fallen below 10c on six nights this month, as late as April 23rd.

Last freeze of the year was on February 18th, pretty early in the season!

First freeze having been on November 29th.

Maximum Temperatures this year:
January: 22
February: 24
March: 27
April:29

April has hit 29 degrees a couple times, and several days with average temps in the 20s. Unlikely to break 30 this month but it should happen early in May
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Old 04-30-2024, 01:11 AM
 
Location: Centre Wellington, ON
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April 28 was the warmest day so far here, with a mean temp of 16.4C, so we're getting close. Forecast for the next week is mean temperatures around 15C, so maybe one day will overperform and we'll get our first tropical day soon. Usually the first one occurs in May here. Other parts of Ontario have probably already gotten there.
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Old Today, 10:58 PM
 
Location: Centre Wellington, ON
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Quote:
Originally Posted by memph View Post
April 28 was the warmest day so far here, with a mean temp of 16.4C, so we're getting close. Forecast for the next week is mean temperatures around 15C, so maybe one day will overperform and we'll get our first tropical day soon. Usually the first one occurs in May here. Other parts of Ontario have probably already gotten there.
We should get our first one in the next week, maybe several.

Forecast mean temps

05/18: 17.5C
05/19: 20.0C
05/20: 21.0C
05/21: 21.5C
05/22: 17.0C
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