How to stop condensation on windows — even every morning

Waking up to windows running with water is one of the most common winter frustrations in UK homes. It isn’t just annoying — over a winter, that water soaks into silicone seals, rots wooden frames and gives mould a foothold on walls and curtains. The good news is that it’s usually very fixable.

Why it happens

Warm air holds more moisture than cold air. When warm, moist air in your room touches a surface colder than its dew point, it can’t hold all that water any more — and the excess condenses onto the surface. Windows are usually the coldest surface in the room, so that’s where it appears first.

Two things make it worse: more moisture in the air and colder glass. Every fix below tackles one or the other.

Why bedroom windows are wet every morning

Bedrooms are where most people notice it, and the pattern is predictable. Overnight, people breathing in a closed room add a surprising amount of moisture — often quoted as around half a pint each. At the same time the heating goes off, the glass cools, and thick curtains trap cold air against it. By dawn the glass is well below the dew point of the room air, and it streams.

That’s why the fixes that work best for morning condensation are about the night: a little background ventilation, a steady low heat rather than heating off, curtains that don’t seal against the glass, and — where it’s persistent — a dehumidifier running in the evening and early morning.

What to do straight away

1. Wipe the windows dry every morning. A squeegee and a cloth, or a window vacuum on Amazon (opens in a new tab) (paid link), takes a minute. Wring the water down the sink rather than leaving it to evaporate back into the room.
2. Open the window or trickle vents for 10–15 minutes after wiping.
3. Open curtains and blinds during the day so the glass warms up. Heavy curtains closed tight against the glass overnight trap cold, still air and make condensation worse.
4. Check your hygrometer. If the room is above 60% in the morning, humidity is the main issue.

Fix it: lower the humidity

Most window condensation in UK homes comes from too much moisture indoors. The usual culprits:

• Breathing overnight in a closed bedroom.
• Washing drying on radiators or airers in living spaces.
• Cooking and showers without fans running.
• Bedrooms without any background ventilation — trickle vents shut, windows never opened in winter.

Start with the free fixes in how to reduce humidity in a room. If condensation still appears most mornings, a dehumidifier is usually the answer — run it in the bedroom in the evening and early morning, set to around 50%. See the best dehumidifier for a bedroom for what to look for.

Useful kit for wet windows

1. 

   To stop it at source

   Quiet dehumidifier for the bedroom

   • Sleep mode with dimmed lights
   • Humidity setting — aim for 50%
   • Choose desiccant instead if the room is cold

   The most reliable fix when windows are wet every morning.

   Compare options on Amazon (opens in a new tab)Paid link
2. 

   To find the cause

   Digital hygrometer

   • Shows whether the room is above 60%
   • Cheap enough to have one per room

   Compare options on Amazon (opens in a new tab)Paid link
3. 

   For single glazing

   Window insulation film kit

   • Creates an insulating air gap on the inside
   • Fits with tape and a hairdryer; removable in spring
   • Renter-friendly

   Warms the inner surface so less condensation forms.

   Compare options on Amazon (opens in a new tab)Paid link

How we choose: these are types of product matched to the criteria in this guide, not individually tested models. Check current specifications and reviews before you buy.

Fix it: warm the glass

• Keep a steady background temperature. A bedroom that drops to 12°C overnight will have far colder glass than one that holds at 16°C.
• Don’t block radiators under windows with long curtains or furniture — they help warm the glass.
• Upgrade old glazing if you own the property. Modern double glazing with a low-emissivity coating stays much warmer on the inside than single glazing or early double glazing.
• Secondary glazing or insulating film is a cheaper alternative for single-glazed or period windows, and suitable for many rented homes.

Don’t ignore mould around the frame

If black spots are already appearing on seals, frames or the wall around the window, clean them promptly and address the humidity — mould comes back quickly otherwise. And if the frame or surrounding wall is damp even when the glass is dry, or it worsens after rain, it may be rain getting in rather than condensation — see how to tell condensation from damp. Our guide on whether dehumidifiers help with mould explains how to clean it safely and stop it returning.