Yes and no. Usually the hens sit tight on the eggs for the last day or so, not getting up to eat or drink at all, but as the weather warms, that would be really hard on the hens. I've had broodies get up to eat/drink in the last days and their chicks hatched fine. A lot of the humidity comes from the hens' body, so when she comes back, the humidity will be fine.
If you think she's abandoning the nest, that's a bigger problem. It's unusual for them to abandon at this stage because they can hear the babies peeping and they're already bonding with them. Make sure she keeps going back to the nest.