The antonyms for the phrase "before dawns" can be "after sunrise," "during the day," or "at noon." These words denote a time period that comes after the break of dawn.
The phrase "after sunrise" refers to the time after the sun has risen above the horizon. It is a period of daylight when the sun is already high in the sky. "During the day" is a more general term that covers the entire period of daylight, from dawn to dusk. "At noon" refers specifically to the time when the sun is at its highest point in the sky, around 12 o'clock noon.
In contrast to "before dawns," these antonyms connote a time of light, warmth, and activity, rather than darkness, stillness, and quiet.