Stormy, April is good, lots of sunshine and cool, around 18-25c pending where in Armenia, although being high altitude country in can change in a short notice, worst month to visit is March, but by end of April it’s very pleasant and colorful, and you get to smell the flowers in the air. I was in Armenia June-July in 2002 and it wasn’t bad, August is very hot and humid. Check out the link bellow it might help. But I agree sep-oct is the best time to visit. Velvet, golden season.
http://www.tacentral.com/weather.asp