Some would say wait till the spring season to install a swimming pool, hopefully finished in time for the warm weather, the bad weather should have eased off by then.
And it should be much dryer (Much Dryer! He cried! When is there a right time in the UK for it to be dry?) I'm pretty sure everyone doesn't know the correct answer to that question, but you would have thought at least the late spring to summer would be dry? Well it does dry up much quicker than in the winter months after a shower (or when it finally stops raining), and we did have temperatures up into the 30's.
Yes true we did for about a week, and even then the temperatures were too high for some types of building works i.
e.
lime or cement mortars dry up too quickly before they've had chance to set, thereby leaving mortars too weak to stay bonded to walls and masonry.
High temperatures can be every bit as detrimental to mortars as frost attack.
One answer is to use panel pools.
No need to bond masonry, or render the walls.
It can be raining and you're still able to erect the panels, as opposed to concrete block and rendered swimming pools, but there is a bigger premium to pay for panel pools.
Concrete block and render pools are a much more permanent and is a stronger structure.
(By the way we are talking about liner pools and not the solid concrete tiled pools when I speak of concrete block and render) There are those who do not want a swimming pool installation to commence in the summer season, because they just don't want the mess and the dust around They just want to enjoy the summer sun, and wait till the end of the summer season to start there project ready for next spring and summer season.
So what are the advantages and disadvantages of having the swimming pool installers in during the spring and summer seasons?

• It's Dryer? Fewer days lost due to inclement weather? Well that theory has gone out the window.
  I've seen more dryer winters than summers.
  The weathermen have not been my favourite person this year All though it's not their fault for the change in weather patterns but we like to blame them for the bad weather.
  
• The pool installer can work longer hours? The swimming pool installer will still work the same hours through the winter as the summer, though occasionally the installer may work later hours and he can still do this in the winter with the correct lighting (On many occasions roadwork's on motorways are performed at night).
  Though some works can't be carried out in artificial light.
  
• Doesn't the frost affect the build? It can do, but when do we get many frosty winter days? How often are the temperatures below freezing? But of course there are means and ways of protecting work from frost attack, and a swimming pool structure is more protected than say an out of ground construction.
  

There is no right time to install a swimming pool.
If you require a swimming pool installed just before the warmer weather arrives then you really should book a date to commence at the last 3 to 4 months of the year and at the beginning of the year.
Also booking a swimming pool installer becomes more difficult as the warmer seasons approach.
The pool installer also has to open swimming pools.
There are also swimming pool repairs and refurbishments to consider.
So if your pool needs repairing, then the best time to repair your pool is out of season.
So really there's no time that is the best time to start a project, and no season is the best season to install or repair a swimming pool.