No party wants another winter election and they not as likely to opt for a less than five year maximum term.
I've never understood this excuse that a 'Winter Election' is somehow different. I manage to go to work, go shopping and do everything else in Winter.
I'm sure I can also manage to call in to the Village Hall on my way to/from any of those activities regardless of the time of year.
We don't live in an age where I have to sit on a rickshaw to travel across rough ground for three days to reach a polling station; so the length of daylight hours and the weather is irrelevant.