Bright
The sun AND the moon are out? With both their light-powers combined, it's incredibly bright outside.
Look up at both of them, hanging out in the sky together. Make them super bright, so bright you have to shield your eyes.
めい, みょう
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.
Depending on where you live, you might want to come up with a different reason for all that brightness in May. Perhaps it's because of Mother's Day, since we all know how brightly mothers shine. The important thing is to remember just how bright the month of May is, for whatever reason!