May ran warm across most of the country this year, and the Pacific Northwest saw an outright mid-month heat wave, with daily temperature records set in Seattle and Portland and Washington logging its warmest May on record. Even where members didn't see records, most of the country is a few weeks into real warmth by now, and for a lot of you that means the first day this season when the cave's cooling system runs longer than it did all winter without quite catching up. If your humidity readings have started drifting even though nothing about your make process has changed, you're not imagining it — you're just meeting your equipment's actual limits for the first time since last summer.
A cave built and calibrated for cooler ambient temperatures doesn't fail all at once in the heat. It slips: a degree warmer than target, a few points drier than you want, a mold you don't usually see showing up on a rind that's been fine for months. Commercial cheese-curing guidance generally points to a fairly narrow band — relative humidity in the mid-40s to mid-50s percent at a room temperature around 68 to 72°F for many facility setups, though the right target depends heavily on the specific cheese and your own cave's build. None of that means your cave is broken. It means the margin you were running on in April has gotten thinner, and small drift compounds over weeks the way it never does over a single afternoon.
What to check before you touch the thermostat
Start with airflow before you start with temperature. A cooling unit working against poor air circulation will run constantly and still lose ground, and it's a cheaper fix than most people assume — repositioning shelving or adding a small fan is often enough to buy back a degree or two. Check your door seals next; a cave that's tight in January can develop a gap by May as materials expand in the heat. And if you're relying on a single humidity reading near the door, move a second sensor to the back of the room for a week and compare — caves are rarely uniform, and the reading you trust may not be the reading that matters for your oldest wheels.
If your cave has always relied on basic heating and ventilation rather than dedicated equipment, this is exactly the kind of stretch where that approach shows its limits — outdoor conditions swing, and your cave swings with them. A modest dehumidifier or humidifier paired with a real hygrometer, rather than a thermostat alone, is usually the cheapest way to decouple your curing conditions from whatever the weather is doing outside, and it doesn't have to be an industrial-scale system to make a real difference in a small room. We know this is an awkward month to be weighing a new equipment purchase against a wholesale cheddar market that's now down seven straight weeks, which is exactly why the airflow and seal fixes above are worth trying first — they cost you almost nothing.
Our Humidity & Airflow Control course walks through this room by room rather than as a general lecture, with worked examples for cave sizes typical of a small or mid-sized creamery rather than a commercial-scale facility. It runs short — most members finish it in an evening plus a follow-up walk-through of their own space — and it's built for exactly this stretch of the calendar, not for troubleshooting after you've already lost a batch.
If you've already lost product to a heat-related humidity swing this month, that's worth a note to our Food Safety Committee as well as a fix to your setup — patterns across several members' caves in the same region can tell us something an individual report can't, and it helps us know when a broader heads-up is warranted. Either way, the fix for most of you is smaller and cheaper than a new compressor. Check the airflow first, then the seals, then the reading you're actually trusting.
The International Cheese Federation (ICF) and More Cheese are entirely fictional. This post is demonstration content created for MemberJunction. All people, organizations, events, courses, certifications, figures, and quotations in it are invented, and nothing here represents a real association, a real business, a real person, or real professional advice.