I was at a nice restaurant last Friday, lovely balmy evening around 25C, and we were almost al fresco sitting at the front of the premises where the doors were wide open. They had a good wine list and great food. The unfortunate thing was the Cab Sav was already warm when delivered, and only got warmer when exposed to the lovely evening air.
The crazy thing is the white wine the ladies had, and I'm not claiming whites are for ladies only (though my mate Brian might), was served chilled and with a wine bucket to keep it cool. So the restaurant took the most care of the cheaper white wine made in stainless steel and that was barely 10 months old, and left the Cab, which the winemaker had nurtured for 3 years, to stew in the warm air.
It's about time Australia realised that "room temperature" for red wine
is too warm, especially in summer. A Cabernet Sauvignon, like most reds, is best served
around 15C, with even 20C really being the upper limit. Pleasant
temperatures for humans isn't so great for red wines.
At home this warm weather I don't stop drinking reds, they either get around 30-60 mins in the normal fridge or come from my wine fridge which is 13C. I then put it in an insulated wine bucket. I also have this little round plastic chiller brick thing that I put in the bottom that is perfectly shaped for the bucket and works better than ice would.
If you overchill your red, it will warm up in the glass anyway, possibly with help from a warm hand. I reckon that's far preferable to sticking in an ice cube, as I've heard of some desperate people doing to a too warm wine. It is after all without external means, considerably easier to warm a wine than to cool it.
The better reds for summer are Grenache, Mataro, Tempranillo, and of course blends of those, but I'd encourage you to always cool your Shiraz and Cabs back down to ~15C to have with a nice BBQ steak or ribs.
I wasn't paying for the reds last week, but I regret not asking for an ice bucket so that I could have enjoyed them as much as the food. I didn't want to seem like a wine wanker, but on the flip side I would not have hesitated to ask for an ice bucket for a Riesling in the same conditions.
There's probably a few guides out there, but I suggest 13C is about as low as you want to go, 15-16C is ideal, and 20C as mentioned before almost too warm.