Mijia

The Mi Temperature and Humidity Monitor 2 is a compact indoor sensor and display for tracking room temperature and relative humidity. The exact Xiaomi model is LYWSD03MMC. Its small 43 × 43 × 12.5 mm body combines a digital temperature/humidity sensor with an at-a-glance LCD-style display, making it suitable for bedrooms, living areas, bathrooms, desks, cabinets and other indoor spaces where environmental changes matter.

Xiaomi specifies a temperature measurement range of 0–60 °C and a humidity range of 0–99% RH. The display resolves temperature changes in 0.1 °C steps and humidity in 1% RH steps. Power comes from a replaceable CR2032 coin cell, and the device communicates over Bluetooth 4.2 BLE rather than Wi-Fi.

The monitor can be added directly in the Mi Home app. Xiaomi's product page states that temperature and humidity changes can be viewed in the app and that the device can store up to three months of environmental data. For smart-home linkage and automation with other devices, Xiaomi describes using a Mi Bluetooth Gateway; this allows temperature or humidity thresholds to participate in scenes such as switching heating or humidification equipment.

Because this is a Bluetooth sensor, remote access and automations depend on having a compatible Bluetooth gateway in the same Mi Home environment. The sensor itself remains useful as a local standalone display even without a gateway. Its compact format and replaceable coin-cell battery make it easy to place in several rooms without wiring, while the simple screen gives immediate readings without opening an app.