It's cold, it's raining, and today is the perfect day to buy a portable AC unit — here's why

(Image credit: Future) Rain is falling outside, and I am wearing two jumpers as I work from my home office. It does not feel like quite the right time to be purchasing a portable air conditioning unit — and yet that is exactly what I am about to suggest.You see, not only are portable ACs finally starting to come back into stock, but some of them are even on sale as part of the Amazon Prime Day sales event (running 6 and 7 October). I've rounded up said deals below. And here's my rationale for buying now, rather than waiting:1. They will sell out againPortable AC units sold out before the first heatwave had even finished, and remained rarer than hen's teeth throughout the rest of the summer. I anticipate a similar scenario next summer. Right now, you have a selection of options to choose from (not just the dregs of what's left in stock), and some of the are even discounted.2. They have winter-friendly functionsYou might not be getting any use out of the AC functions for a while, but a number of these units have secondary functions that will help them earn their floor space during the colder months. Many double as dehumidifiers, which can be very useful for drying clothes indoors during the winter (I made liberal use of this drying method when I lived in a basement flat). A few can also operate as a heater.3. You'll be grateful next summerUnfortunately, scorching summers are set to become the norm, and a portable AC can be a game-changer when it comes to keeping cool. I bought one at the start of the summer and it's one of the best investments I've made — it meant I was able to sleep well at night, even when it was really very hot.• Browse the full Amazon Prime Day saleScroll down for a roundup of the discounted models at Amazon, plus some more full-price options from trusted brands like Meaco and Dreo. My top tip when choosing is to opt for as high a BTU value as you can afford. This stands for British Thermal Units, and it indicates how efficiently the appliance processes air. For a medium-to-large room, a BTU of 10,000 or over is ideal.Cool customersMore Prime Day deals in the UKAmazon Prime: get a 30-day free trialAmazon Devices: up to 67% off Fire, Ring & BlinkAmazon Haul: extra 15% off for Prime membersAppliances: up to 40% off Ninja & De'LonghiBeauty: up to 60% off Philips & Oral-BEssentials: cleaning & groceries from £2Fashion: up to 50% offGaming: record-low Nintendo Switch 2Headphones: up to 50% off Anker & SonyLaptops: up to £800 off Microsoft & AsusTablets: up to 50% off Fire tabletsTVs: from £129.99Vacuums: up to 50% off Shark & DysonWearables: Samsung & Oura from £31 Sign up for breaking news, reviews, opinion, top tech deals, and more. Ruth is TechRadar's Collections Editor, responsible for masterminding TechRadar's approach towards the new Collections format — a themed, curated selection of product recommendations designed to provide readers with an exciting new way to shop for the very best new gadgets and gizmos.