I am a great fan of Macullan Dindarello (I find Sauternes heavy and cloying by contrast) and the “Le Heron” wine at £5.99 at LIDL is a pretty decent alternative, outstanding for the price, not a complex wine, just very nice. A sweet white wine, which if really well chilled, is a great drink in the garden on these hot summer days. That’s what I do, anyway. LIDL give it a rating of 90/100 which I go along with. BTW I drink mostly reds but not in this heat!
Chill your red wines. It’s what they do in hot countries.
I do like a nice Valpolicella in the sun, I first came across this chilling of red wine on a warm rainy day on the Italian lakes and found it very refreshing, but somehow I find as it gets even hotter and hotter my taste in wine for drinking outside on its own gets lighter and lighter and moves through the lightest and freshest of reds, lightly chilled, through to rose and eventually deeply chilled whites as the heat builds up. I never drink anything but powerful reds all winter through, though. I guess each one of us has different tastes.
For me regarding wine temperature, I take my whites out the fridge 30 minutes before serving, for reds I put them in the fridge 30 minutes before serving.