October to February: the short winter and the jobs that belong in it
January is heater season. Unheated pool water in Dubai bottoms out around 18 to 20 degrees, and colder still in inland Al Ain, which is genuinely uncomfortable for most swimmers. Air-source heat pumps are the standard solution and they are efficient in the mild UAE winter, but they need a pre-season service: refrigerant pressure check, coil clean (a summer of dust will have coated it), and confirmation that the flow switch and bypass are set correctly. Book that in November, not the week of the first cold snap, when every heater technician in the country is suddenly busy.
Winter is also when total dissolved solids should be dealt with. After a full summer of evaporation and dosing, a partial drain and refill resets the water chemistry and makes the coming year's chlorine noticeably more effective. Municipal rules on discharging pool water vary by emirate, so a professional who knows where the water is allowed to go is worth having.