Bright
The sun AND the moon are out? With both their light-powers combined, it's incredibly bright outside.
めい
あ, あか, あき
None
When do things start to get bright outside? I'd say when things start getting sunny, and that is the month of May (めい). If you live in the Southern Hemisphere, it's bright in May because of all the snow, or because that's when all the streetlights come on.