Paint drying time around doors and windows that have condensation
Cool temperatures and moisture will affect dry time of latex (water based) paints. A fan heater should help with that. If you are using alkyd (oil-based) paint, cool temps will have the same effect and the heater will help with that; moisture may ruin the paint as it might curdle or wrinkle.

Due to VOC content restrictions, solvents which aid drying are being minimized in oil-based paints; however, there is an additive product called Japan Dryer that will speed dry time, use as directed.