It has nothing to do with the weather as such. It is because of the age of the birds (moulting age) and the season (short days). Pullets will usually lay right through their first winter but the following autumn, they will stop laying and have their first adult moult. They will usually take two or 3 months off, occasionally longer but sometimes less and then recommence laying, usually as the days start to get longer.
Chickens are not egg laying machines, they are animals with reproductive systems that are attuned to the seasons. Eggs are actually seasonal produce. The egg factory chickens are kept in artificial conditions (regulated lighting and some heat) so that their bodies are unaware of the season. This keeps them laying for longer and then they are culled once they start to moult as it is no longer economical to feed them for several months until they come back into lay.
Each subsequent autumn, your hens will moult and take a break from laying and you may find that the unproductive period gets slightly longer each year. As a trade off, you may find that their eggs get slightly larger with each new season.
If you want to keep some production through the autumn/winter seasons then you really need to have pullets coming into lay as your older hens moult.
