Can I continue to use the Retin A .1% and hydroquinone in summer? My melasma gets pretty bad.

You should be on full skin protection in the summer , I suggest you speak to your physician about his recommendation based on your skin type. I also add in chemical peels and clear+brilliant laser and microneedling.  Best, Dr. Emer.

You can continue with those medications in the summer but
sunblock is the most important thing you can do to help. Use a sunscreen with zinc oxide or titanium
dioxide, and keep with the hat and maybe a scarf or collared shirt when in the
sun.