Category Archives: Weather

Climate Change, Weather

Years of anomalous warmth

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Today marks the 866th consecutive day that the rolling 365-day mean has been above 12C, a level that is nearly a degree above the average annual mean temperature for this region.

The next longest period, back to 1960, was 499 days starting on June 9th 2003.

The graph below shows that since around 2015 this 23,644 day period has been stuck in a high rut.

Looking at months on their own it has now been over 20 since this station recorded a month around a degree cooler than average.

The monthly mean temperature anomalies considering 1981-2010 averages.

This September is looking like it will be yet another milder than average month. If the mean for 2024 finishes above the level of 12C it will be the third 12C year in a row!

Prior to this an annual mean of 12C has been recorded on only 11 occasions since 1960: 1989, 1997, 1999, 2002, 2003, 2011, 2014, 2018, 2020, 2022, 2023 .

Weather

The ever wetter autumnal equinox

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The period around the autumnal equinox appears to be getting wetter in this part of the UK.

Since 9am on Sunday 36mm has fallen at Wanstead, some 60% of the monthly total so far! Elsewhere, not too far away near Milton Keynes, Flitwick has recorded 124mm!

A look at the local stats shows that the week either side of September 22nd has been getting wetter since 2010.

A look at the rolling 10-year average since 1960 shows an increase since 2011.

thunderstorms, Weather

September thunderstorms

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This September has seen a lot of convective activity with three days of thunder, already more than the whole of meteorological summer.

The first storms arrived during the early hours of the 8th. Lots of thunder and lightning though only 7.1mm of rain. Further storms bubbled up at 1200 and 1720 with 9.8mm of rain.

Both the 11th and 12th have seen further thunderstorms develop with hail recorded though rain amounts were low; with 0.4mm and 0.6mm recorded respectively.

Here’s a timelapse of cloud activity on the 8th.

Weather

August 2024 in Wanstead

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The mean for August in east London was 19.7C, 1.5C above the 1981-2010 average. It was the 11th warmest back to 1797.

Rainfall of 17.8mm was 35 per cent of average, the driest August for 8 years. It was the 22nd driest back to 1797.

Sunshine at 177 hours was 91 per cent of average. It was the 68th dullest back to 1881.

Thunder was heard once on the evening of the 1st but the core of the storm was south of the Thames with over 50mm at Godstone and New Addington.

A look at the mean temperature shows how much the climate has warmed since the period 1961-90. Though the mean last month was only 0.9C up on the previous 10 years it was actually 2.3C warmer than 1961-90.

9am air pressure was largely below average with a pronounced dip on 24th bringing notably inclement weather for the time of year.

Here’s a few extremes for the month of September across the capital.

Weather

July 2024 in Wanstead

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The mean for July in east London was 18.4C, 0.1C below the 1981-2010 average and the coolest for 12 years.

Rainfall of 67.1mm was 154% of average, 3mm less than last July. Sunshine at 177.3 hours was 92% of average. Duller than average but not as dull as last July.

A largely uneventful month with an absence of thunder and lightning.

As thought months ago with ENSO moving toward neutral August should be the month with the best chance of any heat records being broken.

A look at the mean temperature shows how much the climate has warmed since the period 1961-90. Though the mean last month was 1.3C down on the previous 10 years it was actually 0.7C warmer than 1961-90.

9am air pressure was largely below average until the final third of the month, coinciding with the arrival of more summer-like weather.

Here’s a few extremes for the month of August across the capital.

Heatwaves, Weather

London’s hottest heatwaves under the microscope

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It is no surprise that London’s heatwaves are getting hotter but by what rate are they increasing?

Using a list of hot spells made nine years ago I set out to find how the 30-year trends have moved through the decades since 1852.

The mean of these hot spells has increased from 24.2C in 1851-1880 to 24.9 in 1991-2020, an increase of 0.7C.

Maxima during these spells, on the other hand, has decreased from 32.6C to 31.8C. It should be noted that the spell that produced this area’s hottest ever daily maximum, 40.1C on July 19th 2022, was a 2-day affair that didn’t qualify for the list.

It is the minima that produces the most notable results with average low temperatures increasing over 2C from 15.9C to 18C! The urban heat island in full effect although the estate where a large proportion of these stats are gathered has changed little since it was built in the early 1900s.

Rainfall during these hottest heatwaves is cyclical, in keeping with daily rainfall patterns observed over the same period.

Average sunshine in these heatwaves has shown a slight decline. It is no coincidence that maxima was at its highest during 1911-1950 when there was most sun. Increased cloud cover overall would take the edge off maxima while making the nights warmer.

Weather

Wanstead maxima: 1990 v 2024

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The average maxima in Wanstead so far this summer is 22C, some 0.8C higher than in 1990 – the year an August heatwave saw the UK’s max record broken with 37C in Cheltenham. Media at the time said: “I wonder if the UK will ever see 100F?

The temperature in Wanstead on August 3rd reached 35.8C, my station notes for the day say: ‘dry, sunny and very, very hot’.

Will we see a similar heatwave next month? The weather models tonight suggest not, a flat westerly flow keeping any extreme heat in Iberia.

However, in keeping with summers that occur after an El Nino event, the core of any heat usually happens in late summer – August into September.

Weather

El Niño’s effect on local climate

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With the El Niño–Southern Oscillation (ENSO) trending toward neutral I thought it would be interesting to see how east London’s climate has been affected over the past year.

Using the 12-month rolling mean for this station the difference is an increase of 0.24C. The increase in rainfall, using the 12-month rolling average, is more stark with an increase of 100.9mm.

I had a look at all other El Nino events back to the early 1960s. Some 5 of 7 events saw an increase in the rolling average mean.

The 12-month rolling average rainfall similarly saw an increase in 5 of the 7 events.

The most notable event was May 1997 to May 1998 which saw the temperature increase by 1.67C and a massive increase in rainfall of nearly 300mm.

Weather

June 2024 in Wanstead

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The mean for June in east London was 16.2C, 0.2C warmer than average though the coolest 6th month for 11 years. So yet another warm month – it is now 18 months since we saw a below average one.

Rainfall was on the low side, just 15mm was 29% of average, the driest June for 6 years and 20th driest locally since 1797. Today also moves us into meteorological drought territory – 15 days since there was last measurable rain (>0.2mm)

Sunshine at 204.6hrs was 115% of average, the dullest for 3 years.

The most notable day was probably the 15th with thunder and lightning and a heavy shower at 1230-1300. Further moderate showers in the afternoon.

So, far from being the ‘crap summer’ some are portraying it summer 2024 so far is pretty average here.

More of the same for July. Perhaps a couple of hot days but any prolonged heat staying to our south?

As thought months ago with ENSO moving toward neutral August should be the month with the best chance of any heat records being broken?

Here’s a few extremes for the month of July across the capital.

UK rainfall, Weather

UK rainfall: Seathwaite / Honister v London

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It’s been a wet winter so far. Some 177mm has fallen in Wanstead – already 122 per cent more what falls in an average winter.

But the amount pales into comparison with the Lake District. Since December 1st 1360mm has fallen at Honister, a station close to Seathwaite which proudly proclaims itself as ‘England’s wettest place’.

Over a calendar year the area usually sees 5.6 times the amount of rainfall of London. However, this winter the total of 1360mm makes it 7.7 times wetter! A testament to just how persistent the SW’ly airstreams have been this season. And a reminder that the Lake District is the called the Lake District for a reason.

Data from the excellent Starlings Roost Weather.