Chickens have a natural laying cycle that peaks in the spring and troughs in the fall. The typical flock is at its worst in November, and actually lays better in the depths of winter.
By early spring, long before the weather is nice or the supply of natural food has increased much, the hens start laying like crazy. It’s not about temperature and it’s not about food: it’s about natural cycles. The hens lay their eggs before the food supply is very good because it’s the growing chicks who need easy pickings, not the broody hen, who hardly eats anything when she’s incubating her eggs, anyway. So the natural egg-laying season has to happen before the time of plenty.