I Review Smart Home Devices, and These Are the Best Smart Sensors on Sale for Prime Day

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Prime Day 2025 is here from Tuesday, July 8 to Friday, July 11, and Lifehacker is sharing the best sales based on product reviews, comparisons, and price-tracking tools. 

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New to Prime Day? We have a primer on everything you need to know. Sales are accurate at the time of publication, but prices and inventory are always subject to change.

Many companies make smart sensors, but some are better than others. And Aqara is, in my opinion, the best at it. They make more consumer smart sensors than almost anyone else, and I find them to be consistent and stable. As an added benefit, Aqara’s customer service is a lot better than most. I’d use Prime Day to take advantage of the sales on their best sensors, and here’s what I’d buy. 

Aqara Temperature and Humidity Sensor

I buy these sensors and chuck them everywhere, like my pop-up greenhouse in spring to activate a heater or fan; my chicken coop, so I can get an alert if the girls are too warm; my plant corner, so I know whether to move them; my car, so I know if I need to heat it up before I go someplace; and my outdoor freezer, so I’m alerted if things go sideways. They’re so handy, and they’re 40% off, down from $64.99 to $38.99.

Aqara Water Leak Sensor Kit

Pro tip: You never buy one water leak sensor. You buy a few and spread them around. It’s 2025, so if you don’t have one under your water heater, you’re behind the times. Under sinks, under automatic watering systems, and near your washing machine and fridge are ideal spots. The Water Leak Kit is 35% off, bringing the price down from $56.99 to $35.99.

Aqara Door and Window Sensor Kit

Putting these sensors on select windows gives me a sense of peace: I can check, if I left the house, that I didn’t leave a window open. I can also turn off my A/C automatically if the sensor knows the window is open, or turn a fan on. I like getting a simple notification that a door is left open rather than an alarm going off. The Aqara Door and Window Sensor three-pack is 35% off, from $54.99 to $33.99.

Looking for something else? Retailers like Walmart, Best Buy, and Home Depot have Prime Day competition sales that are especially useful if you don’t have Amazon Prime.

Walmart’s Prime Day competition sale begins at midnight on July 8 and will include deals up to 50% off. It’s an especially good option if you have Walmart+. 

Best Buy’s Prime Day competition sale, “Black Friday in July,” runs through Sunday, July 13 and has some of the best tech sales online. It’s an especially good option if you’re a My Best Buy “Plus” or “Total” member.

Home Depot extended its 4th of July sale through at least July 9, competing with some amazing deals of its own. It’s an especially good option if you’re looking for power tools, appliances, or outdoor equipment.