[z2210558]

It's not just the DHT22's accuracy that's a problem, it's the calibration.

I have 8 of these, and they are up to 30%RH off - both in terms of their readings relative to each other, and relative to the true RH of a saturated salt solution[1]. Moreover, some of them have a strange "stickiness" to certain levels.

I've heard good things about the BME280, and that's what I intend to replace my DHTs with.

[1] See e.g. http://www.omega.com/temperature/Z/pdf/z103.pdf

[gh02t]

Same, I had a lot of trouble with the DHT22 calibration, for temperature as well. And it was nonlinear, so I couldn't just add a correction. I switched to a mix of BME280, Si7021 and DS18B20s. Si7021 is pretty similar to the DHT22 in terms of nominal specs, but it's much better and cheaper.

http://www.kandrsmith.org/RJS/Misc/Hygrometers/calib_many.ht... does a pretty comprehensive review.