I think you're probably right - the crazy weather has affected your plants.

Too much rain can cause yellowing of leaves. Or, when the soil is cold, plants can't access the nutrients they need.

In shrubs like azaleas and rhododendrons, yellowing of leaves denotes a lack of iron. When this happens, iron chelate is applied to the plant and it does the trick.

I think as the weather warms up, your plants will be fine. You might want to side dress the plants with fertilizer (I use dehydrated cow manure) when the weather warms up and they start growing at a faster rate. I wouldn't add it yet, though. The plants are stressed and you don't want to add fertilizer at this time.