The present work proposes a temperature and humidity monitoring system for server rooms based on a wireless sensor network, with alarm sending capabilities via e-mail. Server rooms are among the most important locations in a company since they store information and infrastructure, which guarantee the company’s sustainability. Most of the current monitoring systems are wired and are difficult to install and scale. The proposed system has three wireless nodes connected to a Raspberry Pi 3. Each node consists of an SHT30 temperature and humidity sensor connected via I2C to a WiFi-enabled ESP8266 microcontroller. The sensor nodes and a Raspberry Pi are connected to the same local network and communicate using the MQTT protocol, where the latter works as an MQTT broker. The received data are then sent to a MySQL database located in the Raspberry. Validation results show that the MQTT protocol is robust against high latency and packet loss-prone networks.