Here's a little back story on Hatch chiles if you're not sure what the hype is about: Hatch chiles and New Mexican peppers, usually green, are actually the same as the Anaheim pepper found here in Southern California, but they are usually much hotter. Hatch chiles are not actually a type of pepper, but simply named for being grown in the Hatch Valley, New Mexico. The hot days and cool nights make for a famously delicious group of chiles, but anyone in New Mexico will tell you that New Mexican peppers in general are special.
You can google a list of roasting locations in your area, or pick them up fresh from the market. I was lucky enough to have a wonderful aunt that gave me two vacuum packs of freshly roasted flash frozen Hatch chiles!