If a beach or a pool is not readily available, spending some time at a park or garden is always a good way to relax and enjoy the sun (Portuguese has a saying/proverb that goes O sol quando nasce é para todos, which roughly means “When it rises, the sun is for everyone” [i.e. everyone can enjoy it in roughly the same way] or “When the sun rises, it rises for everyone”).
Interesting enough, while the words for sun ([o] Sol) and beach ([a] praia) are the same everyone, the word for grass is not. EP uses the word [a] relva, while BP uses the word [a] grama (different from the shared word [o] grama, gram, unit of weight).
The words for grassy fields (such as a football/soccer pitch) are vary accordingly; in EP, [o] relvado; in BP, [o] gramado.
As a tribute to hot summers and grass, I recommend you read a poem aptly titled “Summer Moments”, by Fernando Pessoa, one of Portugal’s most renowned poets. This one is in English, but you can find many others in Portuguese. Enjoy :)