Enter the temperature and humidity of the room your capsules are in, or the weather outside and your thermostat setting, and see where the room sits against the storage windows for gelatin and HPMC.
Assumes the heating or cooling adds and removes no water, which is what a plain heater or a cooling-only air conditioner does. A humidifier or a dehumidifier changes the answer, and that's the point of having one.
Windows are the ones the major capsule makers publish for sealed cartons, 15 to 25 °C (59 to 77 °F) and 35 to 65% relative humidity, with HPMC's working range of 10 to 70% shown as the wider band. The outdoor-air calculation conserves absolute humidity using the Magnus formula for saturation vapor pressure. The checker describes the room, not the capsules. Capsules that have been in a room outside the window for days take on the room; capsules in a sealed liner take months. Nothing here is advice about what the capsule's contents do for anyone.