It is the dilemma of every heatwave: buy an air conditioner now, at the peak of demand, or hold out for the September discounts? The question sounds trivial, since sale prices are lower, end of story. The full sums are more interesting, though, and they don't always give the answer you expect.
What actually happens to prices mid-heatwave
Few markets are as seasonal as cooling. When a heatwave lands, demand explodes within days: the most popular models vanish from shelves, promotions are quietly withdrawn, and mid-range portable units sell at full price, when they can be found at all. This summer's reports tell the story: on the best-selling models, shortages are already real, with stock sold out and restock times measured in weeks.
By September the scene flips: demand collapses, warehouses need clearing before heating season, genuine discounts of 20-40% appear on portable units and installers have slots again for fixed systems. On pure ticket price, whoever can wait almost always wins.
With one caveat bargain hunters know well: September discounts apply to what is left. The season's best models, the ones that sold out in July, rarely return in the sales; they are replaced by next year's range at full price. The real discounts are on the second choices, which for most household uses remain perfectly adequate.
See what is actually available
Prices and stock change by the day during a heatwave: the quickest way to get a feel for the market is to browse what is really on offer right now.
But the real sums are not (only) the ticket price
The first thing the «wait for September» calculation forgets: the weeks of heat still to get through. If the current spell runs, as forecasts suggest, well into August, skipping the purchase means choosing to live through them without cooling. The value of nights actually slept and workdays actually worked never appears on a receipt, yet it is the entire reason anyone buys an air conditioner.
The second element cuts against the panic buy: a unit chosen in a rush is almost always chosen badly. Undersized, it will run flat out without ever cooling the room; oversized, it wastes energy on every start. Sizing is done in BTUs against the room's area and sun exposure, and the difference between a portable and a fixed split system is structural. Our air conditioning guide compares the two families, and our portable air conditioner guide covers what these units really deliver.
The third factor: the bill nobody puts in the basket
An air conditioner is paid for twice: at the till and on your electricity bill. A 1,000W portable used without discipline costs over £6 a day at the current price cap if left running; an efficient unit used at 25-26°C, far less than half that. Across three or four summers, the gap in running costs often exceeds the gap in purchase price. It is worth checking against today's electricity prices before, not after, the purchase. And it is the strongest argument against panic buying: the poor model bought dear in July is still a poor model in August.
Worth remembering: at the peak of the wave you pay full price for the worst choice; in September you pay less for the best one, but you cross the summer without it. The rational middle path exists: decide today on the right model (BTUs, energy rating, portable or split), then buy at the first acceptable price, rather than on the hottest day of the year, when everyone else is buying too.
Three profiles, three answers
Those genuinely suffering (young children, older people, home workers under the roof): buy now, but buy right. Shortages hit the best-sellers, not the equivalent alternatives one rung down. Those coping with a fan and closed curtains: waiting for September is a genuine bargain, and leaves time to consider a properly installed fixed unit. Renters: the portable remains the only quick route. All the more reason to size it correctly, because it is the family of appliances where every mistake costs most, both at the till and on the bill.