What it means
Pool season is the stretch of the year when a Scottsdale pool is something you get into rather than look at, and it is shorter than the brochure. The water follows the air with a lag: cold through April, perfect in May and June, then warming past comfort as the nights stop cooling off, until by late July a backyard pool reads about 92 degrees. September brings it back. By mid-October the evenings are the best of the year and the water is already too cold, the small cruelty the first-year note warns about.
Locals use the phrase to mark time (“it’s not pool season yet”) and to settle an argument about heaters. The pool heater is the second half of the term. Resorts run theirs from fall through spring because that is when the guests come; owners run theirs in March for visiting family and in October to steal a month. Everyone else swims when the sun says so.
Where you’ll meet it
In the summer playbook, where the pool is the point of July. In the resort pool guide, where a day pass rents you a heated one. At the city’s aquatic centers, which heat their lap lanes all year. And in every March conversation between a host and a guest about whether the water is “warm.”
Where the word came from
Nobody coined it; the phrase is as old as backyard pools, which in Scottsdale means the 1950s, when ranch-house subdivisions sold a kidney-shaped pool as standard equipment and the resorts made the pool the photograph. What is local is the shape of the season. Elsewhere pool season is summer, full stop. Here summer is the one time the pool stops working as a cooling device, because water that hits 95 at the end of a 112-degree day does not cool off when the overnight low is 88. The real season is the shoulders, May and September, with June the peak and July and August the months you swim at dawn.
The heater entered the vocabulary with the winter visitor. A resort charging high-season rates in February cannot offer a 58-degree pool, so the big properties heat theirs, and Scottsdale’s reputation as a place you swim in winter was built on gas bills. Backyard owners followed when heat pumps got efficient. A heat pump moves warmth from the air into the water and holds 87 or 88 degrees as long as daytime highs clear about 55, which in Scottsdale is nearly every day; it runs roughly $50 to $150 a month in season. Gas heats faster and costs three to five times as much to run, which is why it is the spa heater, not the pool heater. Solar collectors on the roof cost the most to install and nearly nothing to run.
What it is not
Pool season is not the same as lake or river season. The Salt River tubing run opens in May, but the river is snowmelt and stays cooler than any backyard. And “heated” on a rental listing does not always mean free; many hosts charge a daily fee to turn it on. Ask.
The fine print
The law that governs the thing is ARS 36-1681. Where a child under six lives in the home, any pool deeper than 18 inches and wider than 8 feet must sit inside a barrier at least five feet high, with no opening a four-inch sphere can pass, no footholds on the outside, set at least 20 inches from the water’s edge, with a gate that opens away from the pool, closes and latches itself, and latches at 54 inches or higher. If the house forms part of the barrier, the doors to the pool need self-latching hardware and the windows need screens or stops, or the pool needs a motorized cover. The statute lets cities be stricter, and Scottsdale is; its code applies more broadly than the state’s child-under-six trigger, and a non-compliant barrier is a civil citation. The Department of Health Services publishes the notice every pool owner is supposed to receive at purchase. The block wall around the yard usually does the perimeter work; the yard gate is where inspections fail.
The monthly numbers for an unheated Phoenix-area pool, per the local pool builders who track them: 50s in December through February, about 61 in March, 71 in April, 77 in May, 86 in June, 92 in July, 90 in August, 88 in September, 78 in October, 67 in November. Most people stop at 70 going down, which is why the season starts in late April and ends in early October regardless of how pleasant the air is.
Two maintenance facts complete the picture. Every monsoon dust storm fills the skimmer, so a July storm means a morning with the net. And a heat pump without a cover spends most of its energy heating the night sky. For a visitor none of this matters: Eldorado heats its pool year-round for a few dollars, and the resorts sell cabanas in January.