I declare this post fake news because I do not want to believe 40C is happening in July.

...it's not really happening, right!? I already think 30C is bad enough.

looking for cold dinner ideas

Salads ftw!

Upgrade you basic tomato-cucumber-lettuce (and onion, always add onion, red works well if you're not a huge fan) to something a little more interesting by adding things like:

Tinned veg - from peas and corn and beans to new potatoes to asparagus and even palm hearts. Mostly cheap, doesn't rot in the fridge if you forget about it/opt for something else, almost no hassle to use.

Pickles - beetroot and cocktail onions are my go to for this but gherkins and other pickled veg would work too. Both texture and extra tang really boost any salad

Protein - chicken, tuna, cold cuts of ham or whatever, meat substitute like tofu or seiten or fake chicken bits (I often cut up vegan crispy "fillets" and use those). Makes the whole thing feel like a "proper" meal.

Texture - roasted seeds like sunflower and pumpkin but also sesame, pine or even chopped hazel, pistachio or pecan (whatever you can get a hold of really, just roast in pan/under grill for a minute to bring out the oils and make them crunchy). Also dried fried onions that you can buy in a packet are fantastic, as well as those fake bacon bits (they're really just flavoured breadcrumbs!)

Sweet note - in some cases a little bit of fruit (especially if you don't use any other particularly sweet ingredients like beetroot) really elevates a salad. Pick a fruit that isn't mushy, apples and nectarines work well, but I've had grapes and even strawberries in salads and they taste great!

Dressing - down to personal taste of course, and you can buy some really good ones from a jar, but if you want to make a simple one at home, grab a jar with a good fitting lid (or any container you can vigorously mix in), add olive oil (sesame oil works well too, otherwise any flavourless oil should do, just use a little less), vinegar of choice, some mayo and mustard, a touch of maple, golden syrup, or even sugar, and some seasoning (salt pepper garlic powder) and shake/stir well, taste and adjust accordingly.

This all also works if you don't have that first step of fresh veg, I call it "store cupboard salad" and it has gotten me out of a bind on many a warm evening (plus, if it's just you, like it's just me, having to use full size tins means there's enough to last a couple of days!).

(sorry for the ramble, I didn't mean to write this much when I started off lol)