The underdeveloped ones could have been bad seed from last year’s harvest. And other plants look like they are ready to harvest! I have yet to dig down to inspect the bulb, and they are the first and earliest of my garlic to harvest.
A. In my opinion cold weather would not cause any reduction in growth or performance from a garlic clove unless the clove was damaged in some way. The only way to check that is to dig out some poor performing plants and look for a potential problem.
Was the clove too small to begin with? Was there a disease problem on the clove or plant that would cause the plant to perform poorly? Was there an insect problem causing damage to the clove or plant?
The size of the clove is related to plant size and how big your garlic bulb will grow. So if you are seeing differences in growth it would most likely be either a disease, insect or production problem. Bulb mites, onion maggot, nematodes, and some diseases. This can be true particularly if you save seed from year to year and are not careful in planting only the best cloves and make sure they are fully healed (callus over or treat with a fungicide) before planting.
Get adequate room between vegetables so they don't crowd each other. This is particularly true of root crops like onions, garlic, carrots, radishes, turnips, rutabagas, etc.
Make sure you are rotating your vegetables so plants of the same families are not planted in the same spots year after year. It may sound dumb or unnecessary to inexperienced growers but this is vegetable production 101 and a common reason for losses in production in developing countries.
Vegetables in the same plant families should not be repeatedly planted in the same spots year after year. You can or will develop disease and insect problems in those areas that will reduce plant growth and yield. This can lead to a buildup of disease or problems in those beds. Vegetables should be rotated from spot to spot in succeeding years to reduce the disease and insect potential in those spots. So for instance a bed used to grow garlic should not have anything planted in it from the allium family (onions, leeks, garlic, etc.) for at least three years. You can grow anything you want in those spots (tomatoes, melons, etc.) but not from the onion family.
The year following that grow vegetables from the cucurbit (melon, cucumber, squash) family. The third year grow corn in that spot for instance. The next year you can go back to allium. Diseases like white rot can be a very severe problem that may do exactly what you are talking about and prevent good growth of garlic for decades in those spots once the disease is a problem there.
Only use "certified" garlic cloves for seed. The plants used to produce disease and insect-free cloves are certified by an agency or company to be disease-free and you usually eliminate the risk of contaminating your beds. If you do choose to plant your own seed from garlic bulbs, each clove need to be inspected carefully for disease problems before you decide to plant it. Any blemish on the clove that could be disease-related disqualifies the clove for planting but it can be used for cooking since these diseases will never hurt an animal or human.
So I don't think cold caused the problem. I think it is related to a problem that developed during their growth.