I've made some changes in my setup to log environmental weather data:
The sensor's location has been changed to the northern side of our house to keep the time the sensor might be exposed to the sun as short as possible. Additionally I've bought a special housing for the DHT22 sensor with louvers so that air can circulate whilst rain and direct wind is kept out. The white color of the sensor box reflects heat from the sun.
In the future I would like to test some more sensors to log additional environmental data. Therefore I've switched from the WittyCloud board I've used so far to a ESP8266 based NodeMCU V3 board in conjunction with a prototyping base for easy and fast access to the GPIO pins using standard Dupont wires.
The WeatherData.ino sketch on GitHub has been updated too. A watchdog has been added, the ThingSpeak lib is used to publish data and a rudimentary broadcasting of UDP packets with sensor data has been implemented.
Live graph of DHT22's temperature readings in [°C]: