“I know this looks like just another WiFi logger, but this is a little bit more. It uses Thingspeak free service, can be configured through WiFi AP, and uses minimal components. It only needs 3 components: Wemos D1 mini (or nodemcu v1.0 if you prefer), a waterproof DS18B20 and a 5V micro USB wall charger. The picture shows a pushbutton switch as well, but if you use nodemcu, that can be omitted. That is just for erasing EEPROM.”