I Think I Have SAD But Only When It Is

I think I have SAD but only when it is gloomy for a day or two,when sun is out for a few days I'm all happy and fine then just two days of rain or no sun and I'm very depressed ,sun comes out all better again.Its so dramatic in the difference from day to day ,the depression is so up and down,I would like to know what I can take in a herb form as I dont need it all the time ,I live in the south so its mostly sunny ,but it really messes with me when it rains,so I'm just looking for sometimg to get me through a few days or even sometimes one day,I'm 55 ,average weight,smoker,nondrinker,do yoga,meditate,all the things in supposed to do to get me out of my depression time but nothing helps
thanks Darcy Phillips