Why winter air empties the enclosure so fast
A green iguana comes from rainforest canopy, and his skin, lungs and shedding cycle all assume air that feels almost wet — humidity around seventy percent or higher is the working target for this species. Winter attacks that from both sides: outdoor air arrives already dry, radiators and forced-air heating dry it further, and the enclosure's own heat lamp creates a rising current that pulls moist air out through a screen top and drags dry room air in behind it. The result is an iguana living in desert air while sitting under rainforest lights, and the first evidence is usually a shed that comes away in grey patches instead of clean sheets.
Holding moisture in: cover, substrate, water
Start by stopping the loss. Cover part of the screen top — a solid section away from the lamp itself, keeping clear airflow — with a panel so the enclosure keeps more of what you add. Deepen the substrate with a moisture-holding mix such as cypress mulch, kept damp in its lower layers, and it becomes a slow-release reservoir rather than a dry floor. Place the largest water bowl that fits where the warm air passes over it, near but not under the basking spot, so evaporation works for you all day. Living plants rated safe for iguanas add leaf-area humidity and give him humid shade to sit in.
Adding humidity back, actively
Misting still has a place, but aim it at surfaces, not the iguana: wet the plants, walls and substrate until they drip, morning and mid-afternoon, and let evaporation do the slow work. A cool-mist humidifier or an enclosure fogger running in the room beside the enclosure lifts the baseline the enclosure borrows from, which is often the single biggest winter fix, because you are no longer fighting the whole house's dryness at the tank door. A daily soak in lukewarm water supports him from the outside in while the air catches up — many iguanas drink deeply during soaks. What does not work is one heroic misting a day; humidity that spikes and crashes is barely better than none. Service the humidifier itself on a weekly rhythm too — a neglected unit aerosolises whatever is growing in its reservoir, and misting an iguana with mouldy vapour trades one problem for a worse one.
Read the iguana, verify with the gauge
Mount a hygrometer at the height where he actually sits, not up by the lamp where readings flatter you, and check it morning and evening for a week after any change. His body reports the truth over the following weeks: sheds releasing in large clean pieces, bright eyes, relaxed basking. Persistent patchy shed, dull skin and long soaks in the water bowl say the air is still too dry, and the fix is another layer of the same strategy — more cover, wetter substrate, the humidifier closer — rather than hotter lamps, which only dry things faster. Log the readings as winter deepens, and in KinsLe the Care Teams routine pairs each humidity check with the misting round, so the dry weeks never sneak up unrecorded.