I have an similar issue. I just bought two new Anpro BME280 sensors. Inside my house no problems: temperature, pressure, humidity ok. But when I place the sensor outside the house by minus degrees like -1° Celsius (through an ventilation opening) the temperature went down to -140 degrees Celesius (like shown at the screenshot from by Node-Red dashboard). The same problem with the second sensor. Actually I’m thinking about a downgrade to DHT22 because I have no further idea.