After spending more time with the DHT22/AM2302 sensor, I’ve learned the humidity part of the sensor is not accurate at all. The temperature part of the sensor I used was/is quite accurate; accurate enough for a personal weather station, etc.
There are many posts available that describe the process for calibrating this sensor but, I must warn, it’s a long and laborious task.
I have found the following references to aid if you choose to calibrate. Personally, I’ll purchase a more accurate humidity sensor if I need one for a “real” project.
The DHT22/AM2302 sensors have a fairly accurate temperature read; at least the two I tested are.
As for humidity, neither sensor I tested was accurate at all over 50%. If you are needing a higher degree of humidity accuracy you can try the calibration exercises or purchase a more accurate sensor.
All in all, I still recommend this product for learning and testing scenarios.