I've got a weather station outside and I use this add on to bring it into HA. We only had 79.8% coverage during the eclipse, but there was a noticeable drop in temperature!
The measurement of percent humidity is dependent on temperature - cold air can hold less moisture. For the same moisture content, the lower temperature will have a higher percentage of its capacity. If you want a measure that is independent of temperature, look into something like Dew Point.