No, not frost damage. You don't mention if you're fertilizing your tree? If not, then what you're seeing is simply chlorosis. I would fertilize with a water soluble fertilizer like Dyna Gro Foliage Pro, and I would also use a time release product, such as Osmocote Plus (this particular Osmocote product has the proper NPK ratio plus all the micros). You don't mention where you live, but if your tap water is pH is alkaline (over 7.5), you may want to try to acidify your water during the winter. A couple of tablespoons of vinegar per gallon is plenty, and will help with the uptake of nutrients during the winter, when cooler temps, in combination with more alkaline water can cause certain micronutrients to be locked out. And, Meyer lemons tend to need more N than other citrus cultivars, especially when they start producing (and they are prolific producers).

Patty S.

hoosierquilt's,
Thanks on the info. I have use Dyna grow but maybe not enough maybe just once within the last month 1/2. How much should I use and how often. As for my location in located in just south from Riverside CA.

I have a very happy Meyer and a very happy orange tree, even though my soil is alkaline and not great. I mulch them with store-bought compost/planting mix for acid-loving plants. I also occasionally water with the tablespoon of vinegar in gallon of water mentioned by hoosier, and I add a little chelated iron to the water every few months as well. As a result I no longer get those yellow leaves. (I was told that the leaves get yellow sometimes due to lack of iron, but the shortage isn't in the soil--it's either because we overwater, and that somehow makes it difficult to get the iron that is in the soil, or that the soil isn't acidic enough for the plant to use the iron that is present in the soil. I guess this is basically what hoosier is saying.) There are so many badly treated lemon trees in my neighborhood, and I hate seeing those yellow leaves! I always want to sneak out and do some guerrilla fertilizing/acidifying on them! Good luck with your tree. Meyers are divine!