Measuring temperature and humidity is really easy as there are many convenient sensors. Usually to measure humidity along with temperature there are combined sensors used like SHT21. Arduino even have libraries to get things working right away.
ff you want to display things there are more options and of course more work to do. Normally digital sensors are reflected in digital displays, but sometimes we like to look things old fashioned. So in this case analog display can be used. Kerry D. Wong built such device with couple analog displays where one indicates temperature and another humidity. Analog displays are custom made where arrows are controlled with couple servo motors. Driving servos with Arduino is also easy so overall code in project takes only few lines of code. It is set to take readings every 0.5 seconds. Temperature scale ranges from 50 to 95 degrees Fahrenheit and humidity from 5% to 95%.