If you live in California and get a lot of sun on your unsuncreened skin, you might not need vitamin D supplements during summer, only during the winter.

However, if you work full time, and wear long sleeved clothing when out you still might need up to 2,000 IU/day depending on skin tone, propensity to burn, vitamin D deficiency symptoms.

It would be good to have yourself tested at the end of summer to see where you might need to supplement to maintain healthy levels.