Yes it might snow at Doi Inthanon, but it's mostly wet snow I believe. For real snow, there is one montain in Lao that will have snow during winter:
http://www.geonames.org/1657931/phou-bia.html
Personally I don't get the fun in snow. After about five weeks in Thailand and Lao, I just returned home, only to be greeted by bloody snow. I hate snow, I hate cold.
but, doi Inthanon reminds me of a trip we took with about 10-12 people some ten years ago. Even the Thai were laughing at me putting on a coat. Until we got to the summit, and three out of four Thais, plus my Lao boyfriend, made a run for some shop and purchased a coat at inflated prices right on the summit 55555