Every winter, the same thing happened in my house. I would wake up, pull back the curtains, and find the windows streaming with water. Puddles collected on the sills, the frames started to darken, and in one corner a faint patch of mould appeared that I pretended not to see for far too long. I wiped the glass every morning and told myself it was just winter.

It took me a while to learn that condensation is not something you have to live with — it is a symptom with a cause, and once you understand the cause, you can fix it. Learning how to stop condensation on windows in winter starts with one simple idea: condensation happens when warm, moist indoor air touches a cold surface. Your window glass is usually the coldest surface in the room, so it is where the moisture shows up first. You cannot stop winter from being cold, but you can lower the moisture in your air, warm up the glass, and improve the airflow around your windows. Do those three things and the streaming windows mostly disappear.

In this guide I will show you exactly how to stop condensation on windows in winter, with nine practical fixes ranked from the free habits you can start today to the upgrades worth considering if the problem keeps coming back. I will also explain when condensation is a warning sign of a bigger problem, and when it is just a normal part of a cold morning.

Why Windows Get Condensation in Winter

Condensation forms when air cools below its dew point — the temperature at which the water vapour in the air turns back into liquid. In winter, the outside is cold, so your window glass gets cold. Meanwhile, inside your home, everyday life fills the air with moisture: showers, cooking, boiling kettles, drying laundry indoors, houseplants, and even breathing. When that warm, moist air meets cold glass, droplets form. The colder the glass and the more humid the air, the worse the condensation. That is why condensation is worst in the morning, after a cold night, and in rooms where moisture is produced, like bedrooms, kitchens, and bathrooms.

A little condensation on a very cold morning is normal, especially with older windows. But windows that stream with water every day, frames that stay damp, or condensation between the panes are signs that something needs attention. Persistent dampness feeds mould, damages paint and wood, and can even rot window frames over time.

What Is the Right Indoor Humidity in Winter?

As a rough guide, indoor relative humidity of 30 to 50 percent is comfortable in winter. Below 30 percent, the air feels dry and your skin and sinuses may complain. Above 50 percent in cold weather, condensation becomes likely, because the glass surface is cold enough to pull moisture out of the air. The colder it is outside, the drier your indoor air needs to be. On a mild winter day, 45 percent humidity may be fine. On a freezing night, that same humidity can leave your windows soaking.

A cheap hygrometer tells you exactly where you stand. I keep one in the bedroom, because that is where our condensation was worst. If your hygrometer regularly reads above 50 percent in winter, focus on the moisture-reduction fixes below before spending money on anything else.

If your reading stays above 50 percent, that is your cue to work through how to stop condensation on windows in winter from the moisture side first — ventilate, run the fans, and dry laundry outside.

How to Stop Condensation on Windows in Winter: 9 Fixes

  1. Ventilate every morning, even when it is cold: open your windows for ten to fifteen minutes each morning, ideally before you turn the heating up. A short burst of fresh air flushes out humid air that built up overnight and replaces it with drier outdoor air. Cross-ventilation works best: open windows on opposite sides of the house for a few minutes.
  2. Use extractor fans every time you cook or shower: run the fan during cooking and showering and leave it running for at least fifteen minutes afterwards. If you do not have a bathroom fan, open the window slightly during and after a shower and keep the bathroom door closed.
  3. Stop drying laundry indoors (or do it smarter): drying a load indoors can release two litres of water into your home’s air. Dry outside when possible or use a vented tumble dryer; if indoor drying is unavoidable, use one well-ventilated room with the window slightly open and the door closed, ideally with a dehumidifier.
  4. Keep your home heated consistently: homes that swing between hot and cold get worse condensation. Keeping heating on a constant lower temperature, around 18 to 20 degrees Celsius in living areas, keeps the glass warmer and reduces the temperature gap that causes condensation.
  5. Let air circulate around your windows: heavy curtains pulled tight against a window trap cold air and block warm room air from reaching the glass. Open curtains fully during the day and leave a small gap at night; pull furniture a few centimetres away from exterior walls and windows.
  6. Wipe windows down every morning: a microfibre cloth absorbs water without streaks, and a small window vacuum makes the job fast. If you spot black mould, clean it with a mould-removing spray and dry the area thoroughly.
  7. Use a dehumidifier in problem rooms: it pulls moisture directly out of the air, lowering humidity to a level where condensation cannot form. Place it in the worst room, usually a bedroom or basement, and empty the tank regularly.
  8. Seal draughts and insulate the glass: seal gaps with caulk where the frame meets the wall and fit weatherstripping along opening sashes. Window insulation film — a clear plastic sheet shrunk taut with a hairdryer — creates an extra air gap like a second pane and is a cheap temporary fix.
  9. Check for failed seals and consider upgrading: condensation between the panes of a double-glazed window means the seal has failed and moisture is trapped inside; the sealed unit usually needs replacing, though not necessarily the whole frame. Old single-pane windows will always be the coldest surface, so modern double or triple glazing is a long-term fix worth quoting if frames are rotting or seals have failed.

What About Condensation on the Outside of Windows?

Sometimes you will see condensation on the outside of the glass, especially on clear, still nights in spring and autumn. This is actually a good sign: it means your windows are insulating well, so the outer pane stays cold while the inner pane stays warm. Outdoor condensation does not damage your home and usually evaporates by mid-morning. Leave it alone.

That is why outside condensation never worried me once I understood how to stop condensation on windows in winter: the battle is with indoor moisture, not outdoor dew.

When to Worry and Get Professional Help

Get professional advice if you see condensation between the panes, frames that are soft, swollen, or rotting, persistent mould that keeps returning after cleaning, damp patches on walls around windows, or a musty smell that does not go away. Do not ignore mould in a home with children, elderly people, or anyone with asthma.

If the musty smell is coming from a closet rather than a window, my guide to removing a musty smell from a closet naturally may help.

Most homes can learn how to stop condensation on windows in winter with the habits in this guide, but the warning signs above are the exception — they point to a building problem rather than a habit problem.

My Winter Routine Now

Every morning I open the bedroom windows for ten minutes while I get dressed. The bathroom fan runs during every shower and for fifteen minutes after. Laundry goes outside when possible and into one ventilated room with the dehumidifier when it is not. The heating stays steady at around 19 degrees rather than swinging up and down. Curtains are open during the day and pulled back slightly from the glass at night. And on the coldest mornings, I still give the worst window a quick wipe — but that is now a thirty-second job, not a daily flood.

The biggest single change was the morning ventilation. It felt wrong to open windows in January, but within a week the morning puddles were gone. If you try only one fix from this guide, try that one first.

That routine is my answer to how to stop condensation on windows in winter without spending a fortune: it costs nothing, takes ten minutes, and works even in a cold house.

Frequently Asked Questions

Why do my windows get condensation only in winter?

In winter, the glass gets much colder than in summer, while indoor air stays warm and moist from heating, cooking, showering, and breathing. When warm moist air meets cold glass, it cools below its dew point and droplets form. The bigger the temperature gap, the worse the condensation.

Is condensation on windows harmful?

Occasional light condensation is harmless, but persistent dampness can cause mould, damage paint and wood, and rot window frames over time. Mould spores can also aggravate allergies and asthma, so windows that stay wet every day should be dealt with.

What humidity level stops window condensation in winter?

Aim for indoor relative humidity of 30 to 50 percent in winter. The colder it is outside, the lower the humidity needs to be — on freezing nights, even 45 percent can cause condensation on older windows. A hygrometer tells you your exact level.

Does opening windows in winter really help condensation?

Yes. Cold outdoor air holds very little moisture, so a short burst of ventilation flushes humid indoor air out and replaces it with dry air. Ten to fifteen minutes each morning is enough, and it does not waste much heat because the walls and furniture stay warm.

What causes condensation between window panes?

Condensation between the panes means the seal on a double-glazed unit has failed, letting moisture into the sealed gap. Ventilation cannot fix it — the sealed glass unit usually needs to be replaced, though the frame can often be kept.

Should I buy a dehumidifier for window condensation?

A dehumidifier helps a lot in rooms that stay damp despite ventilation, such as bedrooms and basements. It directly lowers humidity, which is the root cause of condensation. Try the free fixes first — ventilation, extractor fans, and steady heating — and add a dehumidifier if those are not enough.

The Bottom Line

Learning how to stop condensation on windows in winter is mostly about managing moisture, not fighting the cold. Ventilate each morning, use your extractor fans, dry laundry wisely, keep heating steady, and let air reach the glass. Most homes see a dramatic improvement within a week of starting those habits. If condensation between the panes or rotting frames show up, get professional advice — but for the everyday winter streaming window, the fixes in this guide are usually all you need. For additional damp-prevention advice, see B&Q’s guide to stopping condensation on windows. Start tomorrow morning: open the windows for ten minutes, and watch the difference.

One last tip for anyone still wondering how to stop condensation on windows in winter: check your windows again after a week of morning ventilation. If the glass is dry, you have found your fix; if not, work through the remaining fixes one at a time.