Citrus tree's are weird. The leaves yellow from to much water and they also yellow from to little water. In your case, it sounds like you have over watered them to me.
Somebody in the forum is going to jump all over me, for what I'm about to say but what little knowledge I do have, comes from hard knocks and alot of practice.
The yellow leaves are GONE, forget about them. Yes, new leaves will grow back unless you over fed them and also burned the branches up. Scratch them, to see if they are still green inside.
As for your watering EEKS, you live where you have DIRT and dirt holds water. I live where there is only sand and even it stays pretty damp, with just 3, 2 gal an hour drippers coming on everyday. Actually, I water at night, [ WHICH THEY SAY NOT TO DO ] and all of my trees seem to like it better and I live out in the desert, where the wind blows and the sun blisters. THE BEST RULE OF THUMB THAT I HAVE EVER HEARD, ABOUT WATERING CITRUS, IS, WHEN THE LEAVES START TO CURL, LENGTH WISE, WATER IT. You have to let the soil almost dry up [ BUT NOT QUITE ] IN ORDER FOR IT TO BREATHE. BELIEVE IT OR NOT. Some of my citrus trees are 26 years old now, I know, I planted all of them, and yes, they only have 3, 2 gal an hour drippers on them that run for 60 minutes in winter and 90 minutes during the summer. I only give them extra water, when they are fruiting and later on, if I feel [ ANY GIVE ] to the skin. Because in my opinion, THE TREE WILL STEAL THE WATER OR JUICES FROM THE FRUIT, IN ORDER TO SURVIVE, A SHORTAGE OF WATER.

just a thought

justnakenny@highstream.net

Some of my citrus have the same symtoms like yours but I don't worry too much because it is winter now. Just like Justnaked said "citrus are wierd". But to make sure checked the pH of your soil. It may be too high alkaline and I add a ironite I bought at Costco. Green veins and yellow leaves says need iron.

I have always wondered why they say "Do not water at night".What happens if it rains at night. Are you supposed to go out an over the trees so they do not get wet? DON"T THINK SO. Its been raining at night for eons. What about fog? This usually occurs at night. The sun comes out and dries excess moisture on the leaves anyway.
I always water my outdoor plants late in the evening with no problems.
Andi

Andi, you really made me laugh reading your post. This is SO true. They say the same about watering roses after dark. But what are we to do if it rains? Trees been around a lot longer than this nonsense about watering after dark.
I guess if the soil is wet and it's going to be chilly at night, it's probably best waiting before giveing plants a drink. I water, feed, and ST whenever I think about it. If it happens to be night, so be it..(though I have a couple plant, non-citrus that are not watered at night)

Mike, most likly your citrus needs acclimating. New leaves should fill in the branch..give it time. It's still cool..In fact I've got the wc on tv and notice it's pretty cool for CA. Do not overwater, that's important. Toni

Thanks everyone. Being a new gardener, I have to learn that it's all about giving plants time.

Like bencelest, I think green veins, yellow leaves mean chlorosis; probably a ph (too alkaline; interferes somehow with taking up iron) or iron deficiency problem. My lemons seem to get this from time to time; more so when it's hot and dry. I don't lose leaves but I try to water in the summer, feed a few ti,es a year, and tolerate it's "weidness".

Gardner:
"Do not water at night" only means to avoid fungus infection because of absence of sun to dry the roots.
You don't want the roots to have wet feet overnight.

A follow up question. If the conditions are corrected (no more overwatering, stress passes etc.)will the trees eventually produce new leaves on the now-bare branches where the leaves have fallen? Thanks.
Mike

Mike,
The branches will produce new leaves provided you do not have twig die back. This is sometimes a result of overwatering. If this occurs you will have brown dead looking branches/branch tips. These should be cut back with sterile cutters until live tissue shows in the branch. If the branch is dead, nothing short of Devine intervention will cause it to grow.
Andi

This thread was helpful to me, thanks! I've got a Meyer dwarf in a pot with slightly yellowing leaves. I'll keep an eye on it. It's got tons of fruit, too.

As far as watering at night, bencelest is partly correct. Fungus really gets started in damp soil, especially if there is any warmth. But what really happens is that the water in the soil is supposed to get taken up by the roots and transpired through the leaves during photosynthesis. All of this requires sunlight. Without sunlight to drive the engines, nothing happens. The plant doesn't take up the water. It's sleeping, sort of. So if you water at night frequently, you can drown your plant, because the roots sit in water all night. It is true that it rains at night, etc. But not every night, all year round.

An occasional watering later in the day is no big deal, if you don't mind a bit of fungus. But to do it regularly isn't good for the plants. Best to water in the early morning hours, so by the end of the day the surface of the soil is dry and so are the leaves, etc.

My meyer lemon tree did the same thing - then I started watering it everyday or every other day, not saturated but a solid amount of water. The leaves are growing in greener, the flowers are coming in abundently and she seems way happier. I water in the day or night - whenever I remember. I live in Los Angeles as well.