These are called Four O'Clocks (Mirabilis Jalapa), a pic from the backyard.
They are appropriately named because they bloom from late afternoon through the night. A night-blooming flower, what a wonderful thing! So much intense color that is mostly not for the benefit of humans. They are supposed to be fragrant, but I have not experienced that. I tend to not sniff a lot of flowers because of wanting to avoid inhaling pollen and/or bugs.