Im not sure which hummzinger you have but I think they are all designed so rain wont drip into the feeder. At least the one I had from nottawabirdsupply. They are also the cheapest and best company to deal with , if you arent happy with your feeder they will take it back no problem. Here is the feeder I had. I sent it back because lots of knats were getting inside but that was also a mistake think I will re-order the excel. I was also surprised at the size of this feeder when I got it and there is enough room between ports for the hummers to not feel crowded. Just my personal opinion.

Here is a link that might be useful: hummzinger excel

Nottawa also sells a 12" dome to protect your feeder from rain but they are sold out at present. The price is $18.96 but Im betting you wont find the rain dome cheaper anywhere else.