--- title: "Washing windows in winter: when you can and what to use" description: "Should you wash windows in winter, and at what temperature? Why not hot water, how to clean glass indoors without condensation, and how to care for frames and seals." url: https://uklid123.cz/en/blog/myti-oken-v-zime-mraz language: en updated: 2026-11-10 publisher: Úklid 1-2-3 (info@uklid123.cz, +420 608 486 486) --- Deep and seasonal cleaning # Washing windows in winter: when you can, how to prevent freezing and what to use You can wash windows from the inside at any time, but not outside in frost. We explain when to tackle the outer side, why to avoid hot water and how to treat the seals. Úklid 1-2-3 editorial team · Published 10 November 2026 · Last reviewed 10 November 2026 · 6 min read ## In short - You can wash the inside of your windows at any time, but it is better to leave the outside for a day when the temperature is above zero. - Do not use hot water on cold glass or frames; window manufacturers warn that the glass may crack. - Squeegee the water off straight after washing and air the room briefly so that moisture does not condense on the glass. - Clean the seals, check their elasticity and treat them with silicone oil or glycerine, but not on the glass. - Car windscreen washer antifreeze does not belong in a flat; some contain methanol. You can wash windows in winter, but not all of them and not in all weather. The inside of the glass and frames can be washed at any time, because you are working in the warmth. Leave the outside for a day when the temperature is above zero. The window manufacturer VEKRA expressly recommends not washing windows at temperatures below zero and warns that hot water on glass chilled by frost may cause the glazing to crack. ## Why frost harms the outside Water applied to cold glass at a temperature below zero will freeze before you have time to squeegee it off. Instead of clean glass, you get a thin layer of ice with streaks. The water may also seep into the grooves of the frame and the seals, where it can freeze. The second risk is thermal shock. In its guidance [How to prepare windows for winter](https://www.vekra.cz/radce/jak-seridit-a-osetrit-okna-pred-zimou/) , the manufacturer writes that glass and frames should not be wiped with hot water, as they could crack. It says the same in the guide [How to clean and wash windows properly](https://www.vekra.cz/radce/jak-spravne-cistit-okna/) . So if you are washing on a cold day, use lukewarm water, not hot. ### When to tackle the outside - On a day when it is above zero outside and no drop in temperature is forecast during the day. - Ideally around midday, when it is warmest, but not in strong sunshine, which evaporates the water quickly and leaves streaks. - In dry, windless conditions, because wind quickly cools the water on the glass. - If the frost lasts for weeks, postpone the outside until the first thaw. A window washed on the inside looks clean anyway. ## Washing windows from the inside: the winter method Indoors, the main problem is moisture. Cold glass is the coldest surface in the room, and water vapour from washing condenses on it. So work with as little water as possible and dry everything off straight away. - Remove flowers and decorations from the windowsill and lay a towel under the window to catch dripping water. - Prepare lukewarm water with a few drops of washing-up liquid. VEKRA recommends lukewarm water with washing-up liquid for glass, frames and sashes, while VELUX states that clean water is normally enough to clean the glass. - Wash the frame and sash first and the glass only afterwards, so that dirt from the frame does not run down onto clean glass. - Dampen the glass with a soft cloth or a sponge without an abrasive side, and squeegee the water off straight away from top to bottom. - Dry the edges of the glass by the seals with a dry microfibre cloth. - When you have finished, air the room thoroughly for a few minutes so that the moisture from washing escapes. VEKRA warns that windows should not be cleaned dry. Always dampen the glass first, and only then squeegee and dry it. ### Equipment - A bucket of lukewarm water and a mild detergent (washing-up liquid). - A soft, lint-free cloth or a chamois leather. - A rubber window squeegee. - Two dry microfibre cloths for the frame and the edges of the glass. - A towel for the windowsill and gloves, if you are using a cleaning product. You will find a detailed method for streak-free glass, including squeegee technique, in the guide [how to wash windows without streaks](https://uklid123.cz/blog/jak-umyt-okna-bez-smouh) . ## What to wash windows with in winter and what not to use In winter the same things are enough as in summer: lukewarm water with washing-up liquid or an ordinary glass cleaner. If you buy an alcohol-based cleaner because it will not freeze, read the label to see whether the manufacturer recommends it for low temperatures as well, and follow its instructions. Even such a product does not solve the thermal shock to the glass or the freezing of water in the frame. Window manufacturers state what to avoid: - abrasive products and rough sponges (VEKRA and VELUX) and sharp objects (VELUX), - aggressive chemicals, thinners and petrol on plastic frames (VEKRA), - hot water on cold glass and frames. Do not scrape ice off the outside of the glass with a scraper or a knife. In its cleaning instructions, VELUX prohibits contact of the glass with sharp and abrasive objects. Wait until the ice melts by itself. ### Beware of antifreeze mixtures from car care products Winter windscreen washer fluids are not intended for use in a flat. If the label lists methanol, do not use them at home at all. According to [NIOSH (CDC)](https://www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750029.html) , methanol enters the body not only through ingestion but also through inhalation and through the skin, and poisoning may only show itself hours later. ### General rules for chemicals - Always read the label and dose according to it. - Ventilate while you work and wear gloves. - Never mix products containing chlorine with acids or with ammonia. Read more in the article on [dangerous combinations of cleaning products](https://uklid123.cz/blog/nebezpecne-kombinace-cisticich-prostredku) . - Try a new product first on a hidden part of the frame. ## Frame, seals and drainage before the frosts Winter is a good time to check how well the window seals. While you are washing from the inside, spend a few minutes on the frame as well. - **Clean the seals** of dust and dirt with a damp cloth and leave them to dry. - **Check their elasticity.** According to VEKRA, a seal should return to its original shape after being pressed and must not be damaged. VELUX states that a worn or damaged seal needs to be replaced. - **Treat the seals** with silicone oil or glycerine, as VEKRA recommends. Apply it to a cloth, not directly to the window. VELUX warns that silicone must not get onto the glass, so work carefully around the glass. - **Clear the drainage holes** in the lower part of the frame. They must stay open, otherwise water stays in the groove. - **Lubricate the fittings.** VEKRA recommends lubricating moving parts, pins and rods with silicone oil. If a sash freezes shut in frost, do not force it open or pour hot water over it. Let it loosen with the warmth from the room. For wooden windows, leave coatings and protective balms until a warmer period. VEKRA states that wood balm should be applied at a temperature of 5–25 °C and out of direct sunlight. ## Why windows mist up after washing and what to do about it When the glass mists up shortly after washing, it is not a washing mistake but a matter of moisture in the room. VELUX writes that condensation on the glazing is a sign that you need to ventilate more often, and describes regular ventilation as the most effective prevention. In its guide [A Brief Guide to Mold, Moisture and Your Home](https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home) , the US EPA recommends keeping indoor humidity below 60%, ideally between 30 and 50%, and drying moisture that condenses on windows quickly. VEKRA advises airing briefly and intensively several times a day in winter. - Wipe condensation off the glass in the morning with a squeegee or a cloth, so that it does not run down to the seals and the windowsill. - Ventilate after cooking, showering and drying laundry. - If your windows mist up all the time, see the article on [condensation on windows and humidity in the flat](https://uklid123.cz/blog/kondenzace-na-oknech-vlhkost-v-byte) . ## Windows as part of pre-Christmas cleaning If you want clean windows for the holidays, divide the work: schedule the inside in any week of Advent and leave the outside for a day above zero, even until after New Year. You will find inspiration for the schedule in the [pre-Christmas cleaning plan for the four weeks of Advent](https://uklid123.cz/blog/predvanocni-uklid) . If you do not want to wash the windows yourself, they are part of [deep cleaning](https://uklid123.cz/sluzby/generalni-uklid) from Úklid 1-2-3. You will find indicative prices by size on the page [how much deep cleaning costs](https://uklid123.cz/kolik-stoji-generalni-uklid) . ## Frequently asked questions ### At what temperature should you no longer wash windows outside? The window manufacturer VEKRA recommends not washing windows when temperatures are below zero. Water on the glass would freeze before you could squeegee it off, and it could seep into the frame and the seals. Leave the outside for a day when the temperature is above zero, ideally around midday and without wind. You can wash the inside at any time, because you are working in the warmth of the room. ### Can I wash windows with warm water in winter? Lukewarm water, yes; hot water, no. In its guidance, VEKRA warns that glass and frames should not be wiped with hot water, as they could crack. The risk is greatest on the outside, where the glass has been chilled by frost. For the inside, lukewarm water with a few drops of washing-up liquid is enough; squeegee it off straight away and dry the edges with a cloth. ### Can I use windscreen washer antifreeze on windows? Do not use it indoors. Windscreen washer fluids are not intended for indoor spaces, and some contain methanol. According to NIOSH, methanol can enter the body through inhalation and through the skin as well. If you need a glass cleaner, choose a household product, read the label, ventilate the room and wear gloves. In frost, though, it is simpler just to postpone cleaning the outside. ### Why do my windows mist up after washing in winter? Cold glass is the coldest surface in the room, and moisture from the air and from the washing condenses on it. Use a small amount of water, squeegee everything off immediately and, after washing, air the room briefly but thoroughly. The EPA recommends keeping indoor humidity ideally between 30 and 50%. If your windows mist up repeatedly, you need to ventilate more often. ## Sources - [Jak připravit okna na zimu – VEKRA](https://www.vekra.cz/radce/jak-seridit-a-osetrit-okna-pred-zimou/) (checked 10 November 2026) - [Jak správně čistit a mýt okna – VEKRA](https://www.vekra.cz/radce/jak-spravne-cistit-okna/) (checked 10 November 2026) - [Střešní okna VELUX – pokyny k používání – VELUX Česká republika](https://www.velux.cz/zakaznicka-podpora/servis-a-udrzba) (checked 10 November 2026) - [A Brief Guide to Mold, Moisture and Your Home – U.S. EPA](https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home) (checked 10 November 2026) - [Methanol: Systemic Agent – NIOSH, CDC](https://www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750029.html) (checked 10 November 2026) Prepared by the Úklid 1-2-3 editorial team with the help of AI and verified against the sources listed. Manufacturers' instructions and regulations change: always follow the current wording of the source and the product label. This article is general information, not professional or legal advice. This article was translated from Czech with the help of AI. The sources are in the original language. ## Would you rather not clean yourself? Choose a service and a part of Prague and you will see an estimated price straight away. We will get back to you with a date; the enquiry is non-binding. 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