The Sensiron SHT45 precision temperature and humidity sensor got featured here a couple of years ago, and wonderful Adafruit has picked up on it, and not only produces SHT4x breakout boards (right), ...

I missed a rather nice precision humidity and temperature sensor from Sensiron when it first emerged. SHT45 is only 1.5 x 1.5 x 0.5 and is specified at ±1.0% relative humidity and ±0.1°C temperature ...