You are going to have to provide more information. Do you mean houseplants? Balcony containers? Garden plants? And what do you mean by 'flowers'? Do you really mean flowers or do you actually mean plants?

One of the best flowers for hot weather is the zinnia. Zinnias thrive in hot, sunny conditions and come in a wide range of colors, making them a popular choice for gardens and landscaping projects. They are also relatively easy to care for and can be grown from seeds or transplants. Other flowers that do well in hot weather include marigolds, sunflowers, and portulaca.