The ThermoPro Bluetooth Digital Hygrometer shows temperature and humidity on a backlit screen and sends the same readings to the ThermoPro app on your phone, up to 260 feet away in open space. It stores two years of data for charts and export, refreshes every 10 seconds, and needs no account to use the app.
It fits growers watching a grow tent or greenhouse, anyone tracking a garage or workshop, and owners of humidors, safes, and instrument rooms who want Bluetooth climate monitors with a built in display. Live app readings come through when your phone is within Bluetooth range.
Specifications
-
Model: ThermoPro TP350
-
Connectivity: Bluetooth to the ThermoPro app, no registration required
-
Wireless Range: Up to 260 feet without obstructions
-
Temperature Accuracy: ±0.9°F
-
Humidity Accuracy: ±2% RH
-
Sensor: NTC sensor
-
Refresh Rate: Every 10 seconds
-
Data Storage: Two years of data with export
-
Display: Backlit screen with humidity shown above temperature
-
Comfort Indicator: Face icon on the display, plus heat index and color comfort scale in the app
-
Placement: Magnetic back and tabletop stand
-
Power: Two AAA batteries, with battery level shown in the app
Checking Garage, Grow Tent, and Storage Conditions From Inside the House
If you keep a grow tent in a spare room, store tools and seed in a garage, or work out of a workshop or shed near the house, this hygrometer lets you check conditions from the kitchen before you walk out. The screen gives you a reading at the spot, while the app shows the same numbers remotely along with heat index and a color comfort scale, which helps you decide whether a hot garage is workable or a space needs ventilation.
Humidity sits at the top of the display in larger numbers, a layout that favors growers and anyone protecting stored goods from moisture. The two year data history lets you compare how a space behaves from one season to the next, so you can plan heating, cooling, or humidity control ahead of time. The magnet holds it on metal shelving or a safe door, and the stand works on a bench.
What to Expect from the ThermoPro Bluetooth Digital Hygrometer in Real Use
Bluetooth pairing is straightforward once you have the right app, though some purchasers found several similar apps in the store and had to make sure they downloaded the official ThermoPro version. Readings take a little while to settle after unboxing, then match wall thermostats closely, and side by side consistency has impressed growers who compared it with dedicated grow room hygrometers. Batteries have lasted well, with an owner replacing them only twice in about a year and a half.
The backlight turns on only when you touch the frame and stays lit briefly to save the AAA cells, which can take a few taps. Owners use it in bedrooms, garages, large gun safes with a dehumidifier, and humidors, and some note it would work well in a greenhouse. A 2024 batch of units in a humidor setup failed within weeks, and ThermoPro replaced all of them without requiring returns. The replacements have worked properly since.
Real-world performance notes sourced in part from verified Amazon customer purchases.
Frequently Asked Questions
Which app does the ThermoPro TP350 hygrometer use?
The TP350 connects to the official ThermoPro app, available free for iPhone and Android. Several apps with similar names appear in app stores, so check that the developer is ThermoPro before installing. The app does not require you to create an account. Once it is installed, turn on Bluetooth, add the device in the app, and it pairs automatically.
How do you turn on the backlight on the ThermoPro TP350?
Touch the white frame around the screen to light the display. The backlight stays on for a short time and then turns off to conserve the two AAA batteries, and the screen returns to its normal unlit state. If it doesn't light on the first touch, tap the frame again. You can also check the current reading in the app at any time without waking the display.
Why does a new hygrometer read high or low when first turned on?
The sensor needs time to adjust to the air around it. If the unit has been somewhere warmer, cooler, or more humid than the space you set it up in, the first readings can be off until it acclimates. Let it sit undisturbed for a while before you compare it with another thermometer or make changes to heating, cooling, or humidity, and the readings will settle to match the room.
