As forecasted nearly a week ago, the south winds are blowing and transporting Mediterranean source air up through the British Isles. Call it an April version of the Spanish plume! Highs today topped close to 21C (70F) at Fyvie Castle, Aberdeenshire thanks to strong sun and some downslope compressional warming off the Grampians. Tomorrow, we should get to similar values here in this ‘sun trap’ area of Scotland.

However the area likely to watch for the warmest temps is Southeast England, we are looking at 22-23C in and around Greater London but be aware of increasingly poor air quality. These stiff SSE winds are blowing over major metropolitan centres such as Paris and so London and the Southeast region’s air quality will be worse than usual.

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After the warmth of today, clear skies, light winds and dry air means a sharp drop in temperature after sunset. Look for -2 to +2C in rural areas but as the sun comes back up tomorrow, temps recover fast.

Big changes come tomorrow evening into Saturday as an Atlantic cold front sweeps through, pushing out the warm, continental air and replacing it with much cooler, fresher and cleaning sub polar ocean air.

As we head for next week, modelling is coming to a more agreed solution with a north-south split. The ridge heads into the continent while the Icelandic low becoming stronger once again. That means a fight but distinctly cooler, windier with spells of rain across Northern Ireland and Scotland while warmer and drier across much of England and Wales as high pressure holds. The GFS has a larger and more expansive low pushing in late next week which could bring cooler with spells of rain to all rather than just the north.

GFS surface through the next 7 day period.

The 5-day GFS ensemble 500mb height anomalies show the big picture well.

While you would typically watch the NAO in winter, you can watch this signal through the warm season to see whether we have a warm, cool, wet or dry overall setup. This positive flat line supports westerly influence with cooler, wetter across the Northern UK, warm, drier in the south.

A strong positive would suggest deeper N Atlantic trough/stronger UK ridge like we saw over the last two summers. Likely in response to the solar max!

See video for the discussion.

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