Sunny Springs Linked to Warmer Weather

By Paul Homewood

As I reported earlier, it was one of the sunniest springs on record this year as well as the warmest. Are the two things related?

I have charted the average of daily max temperatures and sunshine hours in England, and there appears to be a good correlation:

A co-efficient of 0.69 is strong. In short, sunnier weather correlates with warmer weather.

This is not surprising, as the Met Office themselves found exactly the same thing in a 2006 study:

https://web.archive.org/web/20160203112902/https://www.metoffice.gov.uk/media/pdf/q/h/uk_climate_trends.pdf

The daily max is strongly correlated, but there is also a weaker correlation with daily mins. There is no evidence, in other words, that clearer skies result in colder nights during spring.

As the Met Office also suggested, the extra sunshine could be linked to reduced air pollution.

That Met Office study has since been buried and is only archived on Wayback.

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19 Comments

Neutral1966

June 6, 2026 3:02 am

Clearer skies are definitely colder up here in the north. I find it difficult to believe that a study can conclude such nonsense. Okay, some nights when it’s clear but also breezy from the south or SW can be pretty mild; and conversely, some nights that are cloudy under northerly airstream can be chilly, but the coldest nights by far are those under clear, calm skies, especially when influenced by cooler air masses.

Bellman

Reply to Neutral1966

June 6, 2026 3:15 am

I think the issue with correlating clear skies and minimum temperatures is down to the length of the day. Clear skies results in night time temperatures dropping quicker, but when you have a long sunny day, that means starting from a high temperature over a short period of time. It’s the reverse in winter.

Robertvd

Reply to Neutral1966

June 6, 2026 4:42 am

And if the warmer air is brought directly from Africa and settles as a warm air bubble over parts of Britain no doubt you will have warm nights. You were just lucky it wasn’t cloudy because it would even have been warmer at night.
For our cities it is a different story as all the heat stored during the day in our brick, cement,asphalt world is rediated out during the night giving every city its private hot air bubble.
I hope they enjoyed it now they have a colder and wetter start of summer.

Anthony Banton

Reply to Neutral1966

June 6, 2026 6:04 am

A simple algorithm for calculating the overnight minimum that is very effective especially in winter is ….
Tmin = (Tmax+DP)/2 – C.
Where C is a constant (1-5), based on the local mesoscale effects and things like cloud amount and wind strength, and DP the dew point.
EG: for a clear calm night under PM (Polar Maritime England) airmass (away from coasts).
It might be ..
(6+(-2)/2)-5
=-3C
And if the DP was +2 the calculated Min would be -1C

-5

Bellman

June 6, 2026 3:09 am

I’ll have to update my figures when I get back home next week, but from memory there’s definitely a correlation between sunshine hours and temperature in the UK but it isn’t enough to explain all the warming.

Summer is were you see the strongest correlation yet sunshine hasn’t increased much during summer whilst temperatures have been increasing.

Winter months generally have a significant negative trend against sunshine, but the r² is close to zero.

Spring is definitely where we are seeing much more sunshine and the quickest rates of warming. (The lady three springs have been the warmest in record). But it’s difficult to suggest sunshine is the only factor, considering 2024 was a dull spring yet had record mean temperature.

-8

johnesm

Reply to Bellman

June 6, 2026 4:40 am

Sunshine by itself isn’t usually the only factor, or necessarily the largest. However, sunshine hours are often directly correlated to the persistence of high and low pressure areas over a location. A perfect example of that was seen over the southwestern US in March. The anomalies in March 2026 are difficult to overstate. High temperatures in March were often higher than what we saw here later in the year (April, May). The nights were still colder, as the nights were longer then. Naturally, with that incredibly strong and long-lived high pressure, skies were usually clear.

Tim Gorman

Reply to johnesm

June 6, 2026 6:34 am

What you are describing is the variance of the data set of temperatures. That variance is a metric for how accurate a calculated mean actually is. Yet climate science just throws away the variance of the data they use to calculate averages. In essence, they assume zero variance. If the variance of the different daily temperatures is not the same, then the daily temperatures should actually be weighted to reflect the different variances. Yet climate science never does this because they just ignore variances of the data.

Bob Weber

Reply to Bellman

June 6, 2026 5:32 am

2024 was a year when the region was influenced by warmer ocean temperature anomalies too.

strativarius

June 6, 2026 4:43 am

Rainy summers linked to cancelled barbecues.

Denis

June 6, 2026 5:23 am

Due to Clean Air Acts… Yes, and for the US CAA, credit Richard Nixon.

Anthony Banton

June 6, 2026 5:52 am

“That Met Office study has since been buried and is only archived on Wayback.”

No it hasn’t – The MetO has it here ….

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/papers/uk_climate_trends.pdf

-5

strativarius

Reply to Anthony Banton

June 6, 2026 6:23 am

Nobody with a functional neuron believes anything the expensive MO claims.

Redge

Reply to strativarius

June 6, 2026 6:52 am

Nobody with a functional neuron believes anything the expensive MO claims.

I’m not sure about that, Strat, Ed believes everything the MO claims.

Ohhhh….. I see what you mean

Dave Andrews

Reply to Redge

June 6, 2026 8:32 am

You nearly had me there Redge. At first I thought you were alluding to Ed Hawkins of the MO but then twigged you meant mad Ed!

Redge

Reply to Dave Andrews

June 6, 2026 8:41 am

The one and only

At least I hope the only

Jim Gorman

June 6, 2026 6:15 am

Something I see in these graphs and many of the graphs I have examined is a change starting in and around 1980. Prior to that time, temperatures were oscillatory around a mean. But starting in 1980, there is an obvious increase to present. What occurred in 1980 that could cause that?

Here are a couple of examples that show a break at about 1980.

Mark BLR

June 6, 2026 8:47 am

Several media articles, in various western European countries, have tried to link the “May heatwave” to local “this summer will (probably) be hot” predictions.

On the other side of the Channel data from Paris would indicate that weather forecasting on monthly timescales is inherently un-predictable.

The “Parc Montsouris” weather station in (south) Paris has been operating since (1/1/)1900. Selecting years with a “May heatwave”, plus the record-setting 2019 with its “2nd of June spike”, gave me the graph attached below.

A “typical” summer in Paris consists of “pulses” of heat lasting 5 to 15 days, increasing in intensity from mid-June to end-July / start-August, with a pulse “peaking” above 30°C tending to end in a day (or two) of thunderstorms. The intensity gradually decreases from mid-August, though it is often the case that a pulse in September results in an “été indien”.

Note that it is normal for there to be several “gaps / missing pulses”, though obviously the precise timing varies from year to year.

Note also that for me personally 30°C is the nice round number which is the threshold for “canicule”, i.e. “heatwave / too hot”, weather conditions.
.

1922 : After the “May heatwave” reached 34.8°C Tmax went (just) above 30°C on the 1st of June … then never managed to get above 30°C again !

1944 : After the “May heatwave” reached 34.8°C Tmax managed to reach ~32°C for a couple of days in the second week of August. As in 1922 “34.8°C in May” was again the hottest temperature that “summer”.
NB : Paris was liberated that August. The local meteorologists may have been distracted by events all through that particular summer

1947 : After the “May/June heatwave” reached 35[.0]°C there was basically a “typical Parisian summer” as described above … except it set a new “hottest on record” value that lasted for 72 years.

2019 : No “May heatwave”, but a “pulse” at the end of July (finally) broke the 1947 “hottest day EVAH !” record for Paris (along with many other parts of France / western Europe).
NB : The increase in the record for Paris was a “massive” +2.2°C.

2026 : The “May heatwave” lasted a whole week, but peaked at “only” 34.3°C.

Question : What “will” happen for the rest of this Parisian summer ?
Answer : We’ll have to wait until mid-September to find out …

Mr.

Reply to Mark BLR

June 6, 2026 9:08 am

Surely you’re not suggesting that weather can be variable for unforeseen reasons?

Lil-Mike

June 6, 2026 9:08 am

Cloud cover at night blocks outgoing long wave radiation (heat). One really comes to appreciate this in the desert areas. If you look at the data around the max Earth temperature in July 1913 (?). The daily highs were 120s and the overnight lows in the 90s. Except for the night before the max of 134, when the overnight low was in the 1-teens. I surmise cloud cover came in and prevented the nighttime cooling off and the rocky valley started the morning very warm.

Also consider the daily temperature ranges of San Francisco and Sacramento California. In Summer, warm air in the Sacramento Valley rises drawing cooler marine air (ocean temp of 55F), drawing cooler marine air over the bay area. San Francisco will have temperature ranges of 15 degrees (55-70) whilst Sacramento will have temperature ranges of 50 degrees (65-110).