The phrase "on a beautiful sunny day" is correct and usable in written English. It is typically used to describe a pleasant day with warm weather and a clear sky, or to set the scene for a particular event in a story or narrative. For example: "We decided to take a picnic to the park on a beautiful sunny day.".
My friends and I would be the guys going to the lab on a beautiful sunny day to have virtual dogfights on these huge computers.
It got me up early on a beautiful sunny day here in Massachusetts – for what seems like another day of record-breaking high temperatures.
We have turned up to Barratts, the pub-cum-snooker club where we will be trained, on a beautiful sunny day.
He added: "Landing a snapper or two on a beautiful sunny day is what will turn many a child or novice into a fisherman for life".
All against the backdrop of a beautiful sunny day, azure sky.
As we were pulling out of the parking space, he turned on his windshield wipers, even though it was a beautiful, sunny day.
Find joy in even the tiniest things -- your favorite song coming up on shuffle, a funny text from a friend, a beautiful sunny day -- because it adds up.
Thanks to Ludwig my first paper got accepted! The editor wrote me that my manuscript was well-written
Listya Utami K.
PhD Student in Biology, Bandung Institute of Technology, Indonesia