I live in the Philly suburbs, but also have a house in WV about an hour west of DC--so am in similar climate(s.) I don't have any issues with glycerin despite the really low (-6 last week) or high dewpoints in both of these areas. For me, the trick is to use a REALLY rich (moisturizing product) on soaking wet hair prior to adding jelly type product (no chemicals, especially polyquats.) Last week, in the really low dewpoints, I used minute amounts of DTs as my first product on--it worked really well.
3a (Corkicelli), highlighted, fine, low porosity
modified CG, since April '07
CG since 3/11/08

SE PA

HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic (now Hello Curly Curl Stimulater); Botanical Spirits Jellies, CJ Repair Me, Aloe Fix and CCCC