May 1833 and Spring 1837

[Weather-history]

May 1833 has been a month that has fascinated me because of its remarkable CET value with a CET of 15.1, way ahead of any other May in the last 360 years. We experienced the equivalent of this with December 2015.

The readings from were recorded by Orlando Whistlecraft (1810-93) who was a meteorologist and and an almanac compiler. The readings were recorded from Thwaite in Suffolk.

I converted the readings into Celsius from Fahrenheit 

May 1833 (first number is the minimum, the second number is the maximum) 

1. 5.0, 13.9
2. 9.4, 15.0
3. 10.6, 20.6
4. 12.8, 26.7
5. 12.2, 21.7
6. 6.7, 20.6
7. 7.2, 20.6
8. 8.9, 23.4
9. 8.9, 24.4
10. 9.4, 18.9
11. 10.6, 19.4
12. 8.9, 23.9
13. 12.2, 23.9
14. 10.0, 25.0
15. 12.8, 27.8
16. 15.0, 28.9
17. 14.4, 29.7
18. 14.4, 22.2
19. 8.9, 15.6
20. 10.6, 20.6
21. 11.1, 23.9
22. 8.3, 23.9
23. 9.4, 23.9
24. 8.9, 24.4
25. 8.9, 26.7
26. 10.0, 14.4
27. 8.3, 19.4
28. 8.3, 22.8
29. 8.9, 18.9
30. 3.9, 18.9
31. 3.9, 22.2

22 days above 20C

----------

Coldest Spring on record is 1837 with a CET of 5.6

March: 2.3

April: 4.7

May: 9.9

Here are the readings that were recorded from Thwaite for this remarkable season.

First number is the minimum, second number is the maximum

March

1. -2.2, 4.4
2. -0.6, 4.4
3. -0.6, 6.1
4. 2.8, 5.6
5. 0.0, 8.3
6. 1.7, 5.0
7. 0.0, 8.3
8. 0.0, 8.9
9. 3.9, 10.6
10. 2.8, 9.4
11. 0.0, 8.3
12. 0.6, 7.8
13. 0.0, 5.0
14. 0.0, 6.7
15. 1.7, 3.9
16. 2.2, 4.4
17. 1.7, 6.1
18. 1.1, 5.6
19. -2.2, 5.0
20. -3.9, 3.3
21. -5.6, 2.2
22. -3.3, 3.3
23. -7.2, 4.4
24. -5.6, 3.3
25. -2.2, 5.6
26. 0.6, 6.7
27. -8.6, 3.9
28. -0.6, 6.1
29. 1.7, 9.4
30. -1,7, 7.2
31. -2.8, 8.3.     

April

1. -1.1, 8.3
2. -2.2, 8.9
3. 2.2, 7.8
4. -0.6, 7.8
5. 0.6, 6.1
6. -0.6, 7.2
7. -1.7, 5.6
8. 0.6, 6.1
9. -1.1, 3.9
10. -2.2, 5.0
11. -2.3, 7.8
12. -2.8, 5.6
13. 0.6, 6.7
14. 1.1, 10.6
15. -0.6, 10.6
16. 0.6, 6.7
17. 1.1, 5.6
18. 3.3, 8.9
19. 4.4, 10.6
20. 2.2, 13.9
21. 0.6, 11.7
22. 3.3, 11.7
23. 2.2, 7.8
24. 5.0, 14.4
25. 2.2, 15.0
26. 7.2, 15.6
27. 4.4, 14.4
28. 4.4, 16.1
29. 4.4, 13.9
30. 8.3, 14.4

May

1. 7.8, 16.1
2. 6.7, 17.8
3. 6.7, 18.9
4. 5.0, 13.9
5. 5.0, 14.4
6. 3.9, 12.8
7. 1.1, 15.0
8. 6.7, 11.1
9. 1.1, 8.3
10. 1.1, 9.4
11. 1.7, 12.2
12. 5.0, 11.1
13. 3.3, 16.7
14. 4.4, 15.0
15. 6.7, 13.9
16. 6.1, 13.3
17. 4.4, 20.6
18. 6.1, 11.1
19. 4.4, 12.8
20. 5.0, 9.4
21. 3.3, 12.2
22. 3.9, 9.4
23. 5.6, 12.8
24. 5.0, 18.3
25. 7.2, 18.3
26. 6.7, 20.0
27. 5.6, 20.6
28. 7.2, 18.9
29. 6.7, 21.7
30. 1.0, 18.9
31. 7.8, 19.4

Some interesting readings, that mid March to mid April was exceptionally cold for the time of the year.

[Weather-history]

On 08/05/2018 at 12:57, Weather-history said:

May 1833 has been a month that has fascinated me because of its remarkable CET value with a CET of 15.1, way ahead of any other May in the last 360 years. We experienced the equivalent of this with December 2015.

The readings from were recorded by Orlando Whistlecraft (1810-93) who was a meteorologist and and an almanac compiler. The readings were recorded from Thwaite in Suffolk.

I converted the readings into Celsius from Fahrenheit 

May 1833 (first number is the minimum, the second number is the maximum) 

1. 5.0, 13.9
2. 9.4, 15.0
3. 10.6, 20.6
4. 12.8, 26.7
5. 12.2, 21.7
6. 6.7, 20.6
7. 7.2, 20.6
8. 8.9, 23.4
9. 8.9, 24.4
10. 9.4, 18.9
11. 10.6, 19.4
12. 8.9, 23.9
13. 12.2, 23.9
14. 10.0, 25.0
15. 12.8, 27.8
16. 15.0, 28.9
17. 14.4, 29.7
18. 14.4, 22.2
19. 8.9, 15.6
20. 10.6, 20.6
21. 11.1, 23.9
22. 8.3, 23.9
23. 9.4, 23.9
24. 8.9, 24.4
25. 8.9, 26.7
26. 10.0, 14.4
27. 8.3, 19.4
28. 8.3, 22.8
29. 8.9, 18.9
30. 3.9, 18.9
31. 3.9, 22.2

22 days above 20C

 

Some articles from this month from the Guardian/Observer

 

[Weather-history]

On 08/05/2018 at 12:57, Weather-history said:

 

Coldest Spring on record is 1837 with a CET of 5.6

March: 2.3

April: 4.7

May: 9.9

Here are the readings that were recorded from Thwaite for this remarkable season.

First number is the minimum, second number is the maximum

March

1. -2.2, 4.4
2. -0.6, 4.4
3. -0.6, 6.1
4. 2.8, 5.6
5. 0.0, 8.3
6. 1.7, 5.0
7. 0.0, 8.3
8. 0.0, 8.9
9. 3.9, 10.6
10. 2.8, 9.4
11. 0.0, 8.3
12. 0.6, 7.8
13. 0.0, 5.0
14. 0.0, 6.7
15. 1.7, 3.9
16. 2.2, 4.4
17. 1.7, 6.1
18. 1.1, 5.6
19. -2.2, 5.0
20. -3.9, 3.3
21. -5.6, 2.2
22. -3.3, 3.3
23. -7.2, 4.4
24. -5.6, 3.3
25. -2.2, 5.6
26. 0.6, 6.7
27. -8.6, 3.9
28. -0.6, 6.1
29. 1.7, 9.4
30. -1,7, 7.2
31. -2.8, 8.3.     

April

1. -1.1, 8.3
2. -2.2, 8.9
3. 2.2, 7.8
4. -0.6, 7.8
5. 0.6, 6.1
6. -0.6, 7.2
7. -1.7, 5.6
8. 0.6, 6.1
9. -1.1, 3.9
10. -2.2, 5.0
11. -2.3, 7.8
12. -2.8, 5.6
13. 0.6, 6.7
14. 1.1, 10.6
15. -0.6, 10.6
16. 0.6, 6.7
17. 1.1, 5.6
18. 3.3, 8.9
19. 4.4, 10.6
20. 2.2, 13.9
21. 0.6, 11.7
22. 3.3, 11.7
23. 2.2, 7.8
24. 5.0, 14.4
25. 2.2, 15.0
26. 7.2, 15.6
27. 4.4, 14.4
28. 4.4, 16.1
29. 4.4, 13.9
30. 8.3, 14.4

May

1. 7.8, 16.1
2. 6.7, 17.8
3. 6.7, 18.9
4. 5.0, 13.9
5. 5.0, 14.4
6. 3.9, 12.8
7. 1.1, 15.0
8. 6.7, 11.1
9. 1.1, 8.3
10. 1.1, 9.4
11. 1.7, 12.2
12. 5.0, 11.1
13. 3.3, 16.7
14. 4.4, 15.0
15. 6.7, 13.9
16. 6.1, 13.3
17. 4.4, 20.6
18. 6.1, 11.1
19. 4.4, 12.8
20. 5.0, 9.4
21. 3.3, 12.2
22. 3.9, 9.4
23. 5.6, 12.8
24. 5.0, 18.3
25. 7.2, 18.3
26. 6.7, 20.0
27. 5.6, 20.6
28. 7.2, 18.9
29. 6.7, 21.7
30. 1.0, 18.9
31. 7.8, 19.4

Some interesting readings, that mid March to mid April was exceptionally cold for the time of the year.

Guardian/Observer reports from Spring 1837

Late Feb/March

April

May

[Earthshine]

15.1°C is a really extraordinary CET for a spring month.  And even more bizarre how we have never had a May with a 14°C+ CET since.

[Weather-history]

Always fascinated me, May 1833

Reports from May 1833

Canterbury thunderstorm and other storm reports 

 

 

Agricultural

 

Data

Cambridgeshire

Plymouth

 

 

 

Edited May 14, 2023 by Weather-history

[Metwatch]

Just done some graphs on the daily and running values of May 1833 CET against the 1981 - 2010 mean, clearer to see it all.

On 07/06/2022 at 09:05, Earthshine said:

15.1°C is a really extraordinary CET for a spring month.  And even more bizarre how we have never had a May with a 14°C+ CET since.

The CET values were taken from London for 1833 with that mean of 15.1C:

However in London May 1992 and May 2018 were slightly warmer with mean temperatures of I think around 15.4-15.6C at Heathrow. But, London was much smaller in 1833 so it's difficult to truly know if 1833 was that much warmer than 1992 or 2018 thinking about it. Given the stations used for CET values today, I think a modern day CET of 14C would be required to truly beat 1833 for the whole country. The Mays of 1992, 2008, 2018 etc, were probably still quite close to 1833.

Edited May 2 by Metwatch

[Earthshine]

 Metwatch I was under the impression that the CET was three stations, was it really just London?  That's a totally different comparison!

[LetItSnow!]

 Metwatch Hmm, that’s interesting. So up until about 1852 it would surely mean many months from this time and before we’re actually COLDER than they are suggested to be, which is remarkable considering the 19th century was already very chilly. Could also explain some months that synoptically looked colder than the numbers suggested, most commonly found in October I’ve noticed. Perhaps the 1833 anomaly is not quite as anomalous as we thought.

Of course it could also be that the synoptics favoured the anomalies to be higher further north but the reanalysis charts begin in 1836, only three later. Annoying!

It may explain the February 1779 anomaly too.  

Edited May 2 by LetItSnow!

[Metwatch]

13 minutes ago, LetItSnow! said:

Hmm, that’s interesting. Up until when was the CET just calculated for London figures?

Based on that table until 1852, then until 1878 Oxford alone. From 1878 3 stations used for CET and that's also when the maximum and minimum CET series started.

Also just spotted that February 1779 would have been recorded in Rutland, but if it was London then likely a figure over 8C? (still questioning the level of accuracy back then though).

Edited May 2 by Metwatch

[LetItSnow!]

 Metwatch Yeah I edited the message to say 1852 after I saw the image. Seems though maybe the figures from July 1879 to some point in 1852 may be running high which really makes me wonder how cold some of those years, particularly the summers and winters, must have been.

[Relativistic]

Wow, has any adjustment work been done to ensure consistency throughout the series? What use is it to make historical comparisons between months if not?

[Derecho]

3 hours ago, LetItSnow! said:

Hmm, that’s interesting. So up until about 1852 it would surely mean many months from this time and before we’re actually COLDER than they are suggested to be,

I doubt this, they will have taken the temperature anomaly from that station to calculate the CET. The uncertainty comes in when you've got regional differences in anomalies. So for example.

1961-1990 May CET: 11.2C (I think)
London station: Anomaly =  2C above 1961-1990 average.
CET = 13.2C

Now if you had Stonyhurst at the time and the anomaly there was only 1C above average, you'd have a CET of 12.7C (+2C anomaly in London, +1C at Stonyhurst equals an average of +1.5C assuming equal weightings).

Over long time scales any discrepancies should even out generally but the uncertainty for an individual month in those earlier periods will be higher and there may be a higher standard deviation too.

Edited May 2 by Derecho

[Derecho]

15 hours ago, Metwatch said:

Given the stations used for CET values today, I think a modern day CET of 14C would be required to truly beat 1833 for the whole country.

To follow my earlier post, the temperature anomaly in London will have equated to 3.9C above the 1961-90 average there, the raw value would not have been 15.1C that appears in the CET series.

The CET value would have been 11.2C + 3.9C London anomaly = 15.1C. If the raw temperature for London was used you'd see a long sustained upwards spike in CET before it became 3 stations, presumably, especially for summer months.

In order to beat the 1833 record, you'd need an average temperature anomaly of +3.9C at Rothamstad, Pershore College and Stonyhurst, rather then just a +3.9C temperature anomaly over the London area.

That would be difficult even in todays climate, every once in a while you get a month of truly exceptional weather.

Edited May 3 by Derecho