Based on the work of Open Green Energy. https://www.instructables.com/id/Solar-Powered-WiFi-Weather-Station-V20/ Authors of the base code: Keith Hungerford and Debasish Dutta - Excellent work, gentlemen!

Major changes:

• simplified, restructured code (used Adafruit libraries for BME280 instead, sorry for this Keith)
• added relative pressure, dewpoint, dewpoint spread and heatindex calculations
• allow Blynk, ThingSpeak and MQTT data transmission
• redesigned box (simplified printing, less plastic usage, full snap-in)

Changes in V2.3

• included famous Zambretti forecaster (see Blynk example)
• added translation table for Zambretti forecast
• added English language
• added German language

Changes in V2.31

• added Dewpoint Spread
• fixed some minor things

Changes in V2.31 (MQTT version)

• allows to publish data to MQTT broker (alternative .ino file)

Print the box yourself: https://www.thingiverse.com/thing:3551386

Blynk Example (here: German version):

Blynk project settings. Get Blynk in AppStore or GooglePlay and scan QR Code. You might need to purchase Blynk energy to load full project.

Node-Red example showing MQTT messages on dashboard.

ThinkSpeak Example (ThingView iOS):