DD was born in November, so well and truly a summer baby.
I had her in a long sleeve onesie, nappy and gro bag with no sleeves at night. I mad sure she was well and truly out of the swaddle stage by the hottest part. I started unwrapping her during the day for sleeps and then when onto the night once she was happy during the day.
I purchased some snugglebum Pj's for her, they are cotton and she were those alot during summer with a onesie underneath. I mostly used short sleeved onesies under the Pj's and sometimes a long sleeve on the chillier nights.
She used to have her snugglebum Pj's and then into her short sleeve gro bag. I also had some longsleeve jumpsuits as well, for those odd nights when it started warm and got a little bit chilly over night, just not cold enough for the snugtime suit.
I also had a one long sleeve snugtime suit (no legs, just like a gro bag, but warmer), as being Melbourne, sometimes a winter day and night will crop up anytime Or a nice hot day and then bam, a cold change from nowhere!
During the day, she was in a short sleeve onesie and dress, shorts/skirt/skort and Tshirt or whatever took my fancy.

ETA: I also had socks on her some nights, she seemed to have cold feet alot.