A time of hose pipe bans and lazy weekends

[Brownlie]

Two hundred and twelve was a sizzler:
Summer emptied it's hot ash pan all over
greedy asthmatics that sucked life from inhalers
before hitting the nation's emergency rooms.
Cooling beer used up electricity
faster than a Tesla experiment in Colorado;
the sun's reflection lived in every bead of salted sweat.

Everyone's kids looked like sun dried tomatoes
covered in whitewash, sun-factor gazillion. I'm not sure about the word gazillion
Burnt breasts were proudly hoisted - Very interesting sentiment I think you could provide a detail so the reader can infer that the breasts were being proudly hoisted
on freckled forearms and over garden fences. -- I like the detail on the freckled forearms,
The t shirt was in, then off; men strutted like cocks
and showed off six packs, old men under hankies
pulled in one packs, but not for long. -- The humor can be effective here but six packs is a cliche I think you can be more original

Ugly girls were pretty too, in the heat -- I really like this sentiment perhaps you could use details to show how the ugly girls were also pretty. It seems the word "pretty" is being questioned here.nipples drilled into a casual glance, or seasoned stare.
braver ones whipped them out for an even tan.
If you were lucky you got to cream them up.
Sometimes it was scary, the kids giggled
and threw water balloons from upstairs windows
The dog lay in the shade between the garage
and the shed, panting. -- All these concrete details work well

I would avoid adjectives like "ugly" and cliches like "six packs" but you have some interesting ideas that can be expanded on. If you could add a narrative where some sort of action takes place that changes a character or something I think the piece would get stronger.