Sunshine level watch July 2023

[Summer8906]

On 24/12/2023 at 07:50, al78 said:

Nine hours of sun at Charlwood in the first three weeks of the month, that matches my perception it has been a very dull month in Horsham. I hope the entire winter isn't going to be like this, we've had enough of it now.

And given there's been almost none since, and likely to be little more for the rest of the year, could Charlwood end up with less than 20 overall? That sounds shockingly bad even for December, and must surely be a chance of an all-time low record.

[Summer8906]

On 22/12/2023 at 22:34, SummerShower said:

I thought it has been a dark month and this confirms why for this region.

If we can get March 23, April 21 and May 20 sunshine levels this coming spring that will make up for it.

Interesting that Bembridge seems to have something of an anomaly for this region, having around double most other central southern counties.

On 22/12/2023 at 11:35, In Absence of True Seasons said:

Absolutely dire! Unsurprising though. Can't believe that in 20 days, we still have counties that haven't even managed double digits in sunshine hours, which is particularly woeful.

Particularly as Surrey of all places is bottom. The southeast really ought to be the sunniest region this time of year, being amongst the furthest south and closest to drier continental influence.

[Summer8906]

On 01/08/2023 at 16:49, Daniel* said:

Relevant!

 

I realise this is many months old but just going back over this thread, and is of course on-topic for the title.

This graph confirms my suspicion that 200 hours is the threshold for "acceptable" sunshine in a summer month.

Every month with 200hrs+ since 1980 is a month that I would rate a fairly "good" July. Almost every month with below 200 I would rate as disappointingly cloudy.

There is one exception, July 1982 which I'm sure was better than that where I was (NW Sussex). I seem to remember that month as being persistently sunny but not especially warm, but could be wrong. It could have been the school holidays were sunny and the end of term less so, meaning I perceived the month as sunnier than it was.

"Good" Julys by this measurement include 1959, 1964, 1967, 1969, 1971, 1975, 1976, 1977, 1983, 1984, 1985, 1989, 1990, 1991, 1994, 1995, 1996, 1997, 1999, 2003, 2006... and then only 2013, 2014, 2018 and 2022. Thus the frequency has really declined recently compared to the 1983-2006 period. Indeed the 15-year periods 2007-21, 2008-22 or 2009-23 perform worse than most comparable 15-year periods. The only other 15-year period to do as badly for "200 hours of sunshine" Julys is 1960-74.

Edited December 26, 2023 by Summer8906

[In Absence of True Seasons]

33 minutes ago, Summer8906 said:

"Good" Julys by this measurement include 1959, 1964, 1967, 1969, 1971, 1975, 1976, 1977, 1983, 1984, 1985, 1989, 1990, 1991, 1994, 1995, 1996, 1997, 1999, 2003, 2006... and then only 2013, 2014, 2018 and 2022. Thus the frequency has really declined recently compared to the 1983-2006 period. Indeed the 15-year periods 2007-21, 2008-22 or 2009-23 perform worse than most comparable 15-year periods. The only other 15-year period to do as badly for "200 hours of sunshine" Julys is 1960-74

Very interesting. 

This corroborates the feeling I had about the Julys of my childhood years throughout the 90s vs in my teens and now 20s. 

Oftentimes we have a bit of a "rose tinted" view of childhood life, but I do recall the  summer holidays periods as a kid being much sunnier generally than they are now. Which in this case seems to actually be the case. July was always my favourite summer month as a child.

It seems like Julys average temps are now becoming warmer, alongside 'bursts' of heat which are a near guarantee at some point during the month (other than in 2023's July), but on average cloudier / duller too.  

[reef]

58 minutes ago, Summer8906 said:

I realise this is many months old but just going back over this thread, and is of course on-topic for the title.

This graph confirms my suspicion that 200 hours is the threshold for "acceptable" sunshine in a summer month.

Every month with 200hrs+ since 1980 is a month that I would rate a fairly "good" July. Almost every month with below 200 I would rate as disappointingly cloudy.

There is one exception, July 1982 which I'm sure was better than that where I was (NW Sussex). I seem to remember that month as being persistently sunny but not especially warm, but could be wrong.

"Good" Julys by this measurement include 1959, 1964, 1967, 1969, 1971, 1975, 1976, 1977, 1983, 1984, 1985, 1989, 1990, 1991, 1994, 1995, 1996, 1997, 1999, 2003, 2006... and then only 2013, 2014, 2018 and 2022. Thus the frequency has really declined recently compared to the 1983-2006 period. Indeed the 15-year periods 2007-21, 2008-22 or 2009-23 perform worse than most comparable 15-year periods. The only other 15-year period to do as badly for "200 hours of sunshine" Julys is 1960-74.

The maker of that chart has made a classic mistake though. In 2006 the Heathrow sunshine monitor was changed from a Campbell Stokes recorder to an automatic Kipp and Zonen one. The latter under records by over 10% in the summer months, hence why there is a sudden drop-off at that point. Take 2018, for example at 272 hours. On the monthly summaries it is over 280 hours as a correction is applied:

And 2023, 150 hours on the unadjusted figures, above 160 hours on the adjusted:

Edited December 26, 2023 by reef

[Summer8906]

28 minutes ago, In Absence of True Seasons said:

Very interesting. 

This corroborates the feeling I had about the Julys of my childhood years throughout the 90s vs in my teens and now 20s. 

Oftentimes we have a bit of a "rose tinted" view of childhood life, but I do recall the  summer holidays periods as a kid being much sunnier generally than they are now. Which in this case seems to actually be the case. July was always my favourite summer month as a child.

It seems like Julys average temps are now becoming warmer, alongside 'bursts' of heat which are a near guarantee at some point during the month (other than in 2023's July), but on average cloudier / duller too.  

I have the same kind of feeling but the particularly sunny period is less childhood (well, 75-77 were childhood but too long ago for me to remember) and more teens/20s/early 30s. But I guess the teenage and early adulthood years are equally prone to "rose tintedness" as the childhood years. But these stats do indeed confirm that the period to 2006 had a higher occurrence of sunny Julys than that since. Even someone first becoming aware of weather in 1961 during the "cloudy" 60s will have experienced 5 sunny Julys in their first 15 years of weather memories, and 7 in their first 17.

It does seem to be true that your typical modern July has a relatively warm CET, but this is down mostly to heat spikes and mild nights. A month with 20 days of 19C max, 15C min,  7 days of 23C max, 17C min and 4 days of 30C max, 18C min will end up with an impressive mean temp of 18.58 but will still be a month dominated by cool day maxima. (ISTR July 2020, probably the archetypal modern July, being very close to this description).

10 minutes ago, reef said:

The maker of that chart has made a classic mistake though. In 2006 the Heathrow sunshine monitor was changed from a Campbell Stokes recorder to an automatic Kipp and Zonen one. The latter under records by over 10% in the summer months, hence why there is a sudden drop-off at that point. Take 2018, for example at 272 hours. On the monthly summaries it is over 280 hours as a correction is applied:

And 2023, 150 hours on the unadjusted figures, above 160 hours on the adjusted:

Maybe, but many of us do seem to be reporting a perceived drop in July sunshine since 2007 (with the exceptions of 13/14/18/22) so might there be something in it? Are there any accurate figures with this discrepancy accounted for?

Edited December 26, 2023 by Summer8906

[reef]

4 minutes ago, Summer8906 said:

Maybe, but many of us do seem to be reporting a perceived drop in July sunshine since 2007 (with the exceptions of 13/14/18/20) so might there be something in it? Are there any accurate figures with this discrepancy accounted for?

There's very little difference in reality. Each 30 year average has shown an increase over the last without fail for the last few decades. My own figures show little change. No more than 10 hours either way:

1980-89: 189hrs
1990-99: 209hrs
2000-09: 198hrs
2010-19: 198hrs

1989-2006: 208hrs
2007-2023: 198hrs

If you remove the anomolously sunny 2006 and anomolously dull 2020 from each of the figures, they are 201hrs and 204hrs respectively.

There's basically nothing in it apart from the 90s being slightly sunnier than average.

[Summer8906]

8 minutes ago, reef said:

1989-2006: 208hrs

2007-2023: 198hrs

If you remove the anomolously sunny 2006 and anomolously dull 2020 from each of the figures, they are 201hrs and 204hrs respectively.

There's basically nothing in it apart from the 90s being slightly sunnier than average.

I find that absolutely incredible as my perception has been that 1989-2006 was very much sunnier in July than 2007-23. Perhaps local effects to this area (south Hampshire)? Perhaps increased Atlantic airmasses blowing in straight off the Channel since 2007 has caused a disproportionate increase in cloudiness since 2007? Perhaps a backing of mean summer wind direction from WNW to a cloudier WSW (old pressure charts suggest WNW used to be the mean summer wind direction, due to Azores high influence).

It seems to be the case that the east of England, further away from Atlantic influence, isn't doing so badly for summer sunshine these days from reports on here.

In terms of pressure patterns, my perception has been that extensions of the Azores high into S England in July have become considerably less frequent since 2007, and cloudier, weakly-cyclonic types with the Azores high more remote, and higher pressure over continental Europe (forcing the SW-ly) have become more common. It also seems to have been the case that droughts and extreme heat over central Europe have become more common in that timeframe, while the old WNW-ly pattern formerly produced periods of cool wet weather at times there.

Edited December 26, 2023 by Summer8906

[reef]

7 minutes ago, Summer8906 said:

I find that absolutely incredible as my perception has been that 1989-2006 was very much sunnier in July than 2007-23. Perhaps local effects to this area (south Hampshire)? Perhaps increased Atlantic airmasses blowing in straight off the Channel since 2007 has caused a disproportionate increase in cloudiness since 2007? Perhaps a backing of mean summer wind direction from WNW to a cloudier WSW (old pressure charts suggest WNW used to be the mean wind direction, due to Azores high influence).

It seems to be the case that the east of England, further away from Atlantic influence, aren't doing so badly for summer sunshine these days from reports on here.

In terms of pressure patterns, my perception has been that extensions of the Azores high into S England in July have become considerably less frequent since 2007, and cloudier, weakly-cyclonic types with the Azores high more remote have become more common.

That's the issue with perception, it often fools you. The 1989-2006 period was sunny, but I suspect people remember the spell of four good ones on the bounce from 1994-1997, as well as the good 1999 and great 2006. However in there were some downright rotten months like 1992, 1993, 1998, 2000 and 2002 - all of which were duller than any July between 2007 and 2019 here.

[SunSean]

December sunshine table complete. Very dull month for most!

[reef]

We somehow hit 57 hours here, which is 95% of average.

Despite coming out top its still felt dull. I imagine it's felt much like December 2002 did here which had similarly low levels of sun like many places this month.

[reef]

Here it is in all its glory:

We did quite well, but it was still rubbish!

[Freeze]

On 02/01/2024 at 13:01, reef said:

Here it is in all its glory:

We did quite well, but it was still rubbish!

Wow, don't think it's often I'm in the dullest area of the country!

[B87]

On 26/12/2023 at 11:51, reef said:

The maker of that chart has made a classic mistake though. In 2006 the Heathrow sunshine monitor was changed from a Campbell Stokes recorder to an automatic Kipp and Zonen one. The latter under records by over 10% in the summer months, hence why there is a sudden drop-off at that point. Take 2018, for example at 272 hours. On the monthly summaries it is over 280 hours as a correction is applied:

And 2023, 150 hours on the unadjusted figures, above 160 hours on the adjusted:

London's actual July sunshine totals since 2006 are as follows:

2006: 302.2 hours

2007: 182.6 hours

2008: 196.1 hours

2009: 178.2 hours

2010: 184.7 hours

2011: 197.3 hours

2012: 184.4 hours

2013: 294.1 hours

2014: 272.5 hours

2015: 214.3 hours

2016: 207.0 hours

2017: 201.9 hours

2018: 298.3 hours

2019: 219.3 hours

2020: 194.7 hours

2021: 195.0 hours

2022: 249.8 hours

2023: 169.5 hours

Not so much of a sudden drop off any more, though still showing a duller period between 2007-2012. The 91-20 July average is just shy of 220 hours, though August has seen a decrease to 203 hours.

Edited January 10 by B87