You could go to kmart or target and get one of those 3 gauge sets mounted on a wood plaque temp, baro, humidity.
What you need for predicting is CORRECTED barometric press. Which is what the weater stations calculate for you.
Also I have a slide rule type calculator to get density altitude that comes with a cert. barometer and a temp/humidity gauge. PM me if you are interested. I will sell the Hot Sports weather/ET predictor for $125 + shipping. Don