When will London's Polar Spring 2021 end?

I think we will end up with one of the coldest summers on record, with temperatures struggling to get above 80f at any point. Maybe spring 2022 before we see anything normal again.

Extremely optimistic; UKMO going for a cold and wet June.

You think it will be 3-4c below normal for the rest of human history?

Where's the "when B87 travels to northern Scandinavia" option? That one usually works.

1 August. Both August and September will be among the warmest on record. But August will of course be cloudy.

I picked 2022, but in reality this is the new normal & re-setting London (& the rest of the UK) to its true cold epoch climate. Global cooling is very real, soon the Gulf Stream will stop completely & the whole of the British Isles will return to their true climatic state. Frost fairs will once again become the norm on the Thames in central London & winters will feature almost complete snow cover from October-April. The Canary Island Date palms in London & other current milder locations will soon be replaced by Norwegian Spruce & the city dwelling red fox, will die from cold & be replaced by the white arctic fox.
This of course will have some benefits, in that many who have traveled across the Mediterranean from sub-Saharan Africa for a new & better life in the UK, will all seriously reconsider their inital trips & a mass exodus down to the south of France will commence.

This is the new normal. Covid was just the start, this is the stark, bleak reality now of life in the UK.

Sorry to burst your bubble, but

The Italian South—and by extension Malta will turn into the true subtropical paradise it really is, with lions—and other tropical animals such as green jays, crocodiles, parrots and flamingos being able to thrive once again, and once the Atlantic Multidecadal Oscillation shifts away from the warm phase, the Italian South, and the rest of Europe will return to the wetter, natural climactic state without any drought. Monsoon-like thunderstorms will be commonplace, and 365-day growing seasons will exist as far north as Florence or Bologna. Subtropical/tropical plants such as jacarandas, bay laurels, dragon fruit trees, as well as a myriad of palm trees, such as coconuts will replace the common Mediterranean vegetation. And to underscore of just how subtropical the Italian South really is, the islands of Lampedusa, Malta and the Pachino and Agrigento coasts will be one of the few places in the world to have a TROPICAL climate OUTSIDE the tropics.

Unfortunately Malta will soon cease to exist, this is the real reason I am heading back to the polar climes of the UK. There has been record levels of siesmic activity centred around Sicily & Malta, Mt Etna has been kicked into more activity & soon a mega, catastrophic eruption will happen. The initial blast will will be devastating for much of Sicily & southern Italy & a tsunami will be triggered which will wipe out Malta, as well as the Islands of Lampedusa & Pantelleria. The fall out from the eruption will ground flights indefinitely across Europe & the Middle East & the sun will be obscured for many, many months. Record cold temperatures will occur all around Europe. There will be no summer & winter will arrive early & will last for at least the next 2 years. Anyone who survives the inital eruption in the central Mediterranean will need to flee either far north or far south. Africa will have to prepare itself for mass immigration & for once Sweden & Finland will look like a nice place to live.
Benny Boy, I'm telling you this because I love you, please, please leave Rome as soon as you possibly can, before it is too late.

No. Your wrong. UK_Palms & myself have joined forces, along with Wilko & OwenC. We are the "Climate Truthers". Look out for us soon on YouTube.

Don't say I didn't warn you Benny Boy.