Misted Windows in Winter: Why It Happens More in Cold Weather

Misted windows are a common issue during winter, and many homeowners first notice the problem when temperatures drop. If your double glazing looks cloudy or fogged up between the panes and wiping it does nothing, it is usually a sign that the sealed unit has failed.

At MK Doors & Windows, we see a clear increase in misted window enquiries across Milton Keynes during the colder months. This guide explains why winter highlights the issue, what it means for your windows, and how it can usually be fixed without replacing the entire frame.

What Causes Windows to Mist Up?

Double glazed windows rely on a sealed gap between two panes of glass to trap air or gas for insulation. Over time, that seal can break down due to age, weather exposure, or movement in the frame.

Once the seal fails, moisture enters the unit and becomes trapped between the panes. This causes the misting or fogging effect that cannot be cleaned from either side of the glass.

Why Misted Windows Are More Noticeable in Winter

Bigger temperature differences

During winter, the contrast between warm indoor air and cold outdoor temperatures increases. This highlights weaknesses in sealed units and makes misting more visible.

Higher heating use

When your heating is on more often, the inner pane warms up while the outer pane stays cold. This can make failed units stand out, especially in the early morning or evening.

Reduced ventilation

Homes are usually kept more closed up in winter, which can raise internal humidity levels. While this does not cause sealed unit failure, it can make existing problems easier to spot.

Does a Misted Window Mean You Need New Windows?

In most cases, no. If the window frame is still in good condition, only the sealed glass unit needs to be replaced. This restores insulation and visibility without the cost or disruption of a full window replacement.

Our Sealed Unit Replacements service is designed specifically for this situation and is one of the most cost effective winter upgrades available.

Signs Your Sealed Unit Has Failed

• Cloudy or foggy patches between the panes.

• Condensation trapped inside the glass.

• Windows that feel colder than others in the same room.

• Higher heat loss near the affected window.

What Happens During a Sealed Unit Replacement?

The existing glass unit is carefully removed and replaced with a new sealed unit made to the correct size and specification. The frame remains in place, and the window is checked for alignment, sealing, and smooth operation before the job is completed.

This process is quick, clean, and far less disruptive than full window replacement.

What If the Issue Is Not the Glass?

Sometimes a window may feel cold due to draughts or alignment issues rather than a failed sealed unit. In these cases, replacing the glass is not necessary.

Our Window and Door Repairs service covers seal replacement, hinge adjustment, and locking mechanism issues that can all contribute to winter heat loss.

Can Secondary Glazing Help?

For older properties or homes where replacing the glass is not suitable, secondary glazing can provide a noticeable improvement in warmth and comfort. It adds an internal layer of insulation without altering the external window.

You can find more details on our Secondary Glazing page.

Get Misted Windows Fixed This Winter

Misted windows do not need to be lived with through the winter months. Whether you need a sealed unit replacement or a simple repair, our team can advise on the best solution for your home.

To arrange a free quote, visit our Contact Us page or view recent work in our Gallery.