I started to study humidity in a woodland. We bought a cheap meter put it under a cover but in free air and it went to max 95% and stuck there. We took it indoors and dried it but once outside same again.
Yet at home I have a weather station and the outside bit does not get stuck at 95%, but 70% is about lowest reading outside, looking at the dew point it will vary from zero to 14 degs C in November.
The dew point in the house is around 2 degs higher than outside, but of course we heat the house in winter. So in Winter looking at 35 ~ 55% Summer will see higher readings 70% is about the max recorded.
I use excel to work out the dew point "temperature - (100-humidity)/5" gives approx dew point. The more air transfer the lower the relative humidity so high humidity normally means poor ventilation. Father-in-laws house is silly high, he has sealed doors triple glazing and gas cooking. We have just double glazing poor seals on the doors and electric cooking.