It’s 3:00 AM. You’re sound asleep, finally getting the rest you need. Suddenly, you’re jolted awake by what feels like a splash of cold water going directly into your nose.

If you’ve experienced this, you know how jarring this can be. You rip the mask off, sputtering, wide awake, with your therapy ruined for the night.

This phenomenon is called "Rainout," and while it can happen year-round, it is the number one complaint we hear from CPAP users during the winter months.

Rainout doesn’t just make sleep uncomfortable; it can interrupt therapy pressure, affect humidity delivery, and in some cases, damage your equipment.

Fortunately, this can be pretty easy to solve. Rainout doesn’t mean your machine is broken. It’s just simple physics.

Your CPAP humidifier is pumping warm, moist air into the tube. When that warm air travels through a hose surrounded by a chilly winter bedroom, the air cools down rapidly. It loses its ability to hold moisture, and that humidity turns back into liquid water—right inside your hose.

You could turn your humidifier off, but then you’re dealing with a parched throat and dried-out sinuses. You shouldn't have to compromise.

Use this 5-step checklist to keep your humidification high and your tubing dry all winter long.

Rainout At a Glance

Rainout = condensation inside your CPAP tubing or mask components.

Winter makes it worse because:

• Bedrooms often get colder overnight (thermostat setbacks, drafts, exterior walls).
• Hoses are exposed to colder air, especially near windows.
• The temperature difference between humidified air and the hose wall becomes larger, which increases condensation.

The 5-Step Rainout Checklist

1. Optimize Your Humidity Settings

Your CPAP’s humidifier is essential for comfort, but it’s also a key contributor to condensation. The higher your humidity setting, the more moisture travels through the hose—and when that moist air hits colder tubing, water droplets form.

Start simple:

• Lower the humidity setting by one level at a time until you find a balance of comfort and dryness.
• Adjust your tube temperature upward slightly to keep the air warm enough to hold moisture.

Expert Tip: If your air feels too dry after lowering humidity, bump the tube temperature up one notch instead of raising humidity. This keeps your therapy air warm and comfortable without adding extra moisture.

2. Use Heated Tubing (Not Just Heated Humidification)

Even with the perfect humidity setting, standard tubing can cool the air too quickly. The best solution is heated tubing, which maintains a stable temperature from humidifier to mask—preventing moisture from ever condensing.

Heated hoses like the ResMed ClimateLineAir or Philips Heated Tube are designed to sync automatically with your CPAP’s temperature controls. They keep airflow consistent and the inside of your hose dry.

When setting up:

• Connect the heated tube directly to your humidifier outlet.
• Keep the hose straight and avoid tight loops or kinks.
• Check that your machine recognizes the heated hose mode in its settings menu.

3. Keep Your CPAP at or Below Bed Level

This step might surprise you: your machine’s placement influences how condensation behaves. Water naturally flows downhill, so if your CPAP sits higher than your mask, any condensation that forms will trickle right toward you.

To stop that backflow:

• Place your machine on a nightstand below mattress height.
• Route your hose upward from the machine, then over your head or on a hose lift.
• Use gentle loops instead of sharp bends to encourage airflow and prevent pooling.

4. Keep the Room Comfortable and Consistent

Winter temperature swings are a silent culprit behind most rainout complaints. The greater the difference between room temperature and your CPAP air temperature, the more likely condensation will form.

To maintain balance:

• Keep your bedroom around 68°F (20°C) overnight.
• Avoid placing your CPAP next to exterior walls or directly under vents.
• Use a hose insulation wrap for additional warmth if your bedroom stays cold.

Even a small temperature drop—just 5 degrees—can trigger condensation. A consistent room environment helps your humidifier and heated hose work effectively together.

5. Maintain and Inspect Your Equipment Regularly

Rainout isn’t just about the season—it’s also about your setup’s condition. Loose seals, worn tubing, or mineral buildup in the water chamber can all impact humidity delivery and cause inconsistent moisture levels.

Keep your system in top shape:

• Rinse and air-dry tubing and the water chamber daily.
• Check connections for looseness or leaks.
• Replace tubing every 3–6 months and humidifier chambers at least once a year.
• Use only distilled water to prevent mineral scale that tamps humidity accuracy.

Your Rainout-Free Winter Starts Tonight

You don’t have to trade winter comfort for consistent sleep therapy. By fine-tuning humidity, upgrading your tubing, adjusting placement, controlling your environment, and maintaining your gear, you can virtually eliminate condensation all season long.

If you’re still battling rainout after making these changes, don’t go it alone—our experts at CPAPmyway can help personalize your setup.