Wind beats sunshine for drying laundry. Humidity, rain probability and temperature — what you actually need to check before hanging out a load.
Check if today's good for hanging washing →These are approximate drying times for a typical cotton load (t-shirts, shirts, lightweight items). Towels and jeans take 30–50% longer; synthetics dry faster. Times assume a full washing line in open air.
| Weather combination | Clothes | Towels/heavy items |
|---|---|---|
| Sunny + breezy (15°C+, 10–18 mph, humidity below 60%) | 1.5–2.5 hrs | 3–4 hrs |
| Sunny + still (18°C+, under 5 mph, humidity below 65%) | 3–4 hrs | 5–6 hrs |
| Overcast + breezy (13°C+, 10–15 mph, humidity below 70%) | 3–5 hrs | 5–7 hrs |
| Overcast + still (10–14°C, under 5 mph, humidity 65–75%) | 6–8 hrs | May not dry fully |
| Cool and breezy (5–9°C, 10+ mph, dry) | 5–7 hrs | 7–10 hrs |
| Humid and still (any temp, humidity above 80%, under 5 mph) | Very slow / won't dry | Not recommended |
| Rain risk above 50% | Don't hang out | Air indoors on a rack |
Most people assume a sunny day is the best for drying washing. The truth is more nuanced — and wind is the dominant factor, not sunshine.
When wet fabric dries, water molecules evaporate from the surface into the surrounding air. But there is a limit: the layer of air immediately surrounding each garment quickly becomes saturated with water vapour, which slows further evaporation. Wind continuously removes this saturated air layer and replaces it with drier air — giving the evaporation process a fresh starting point repeatedly. This is why a cool, breezy, overcast day often dries washing faster than a warm, sunny, still one.
Sunshine helps in two ways: it warms the air (warm air holds more water vapour — it has greater capacity to absorb moisture from fabric); and UV from sunshine has a mild bleaching and antibacterial effect on whites, which is a genuine benefit. But these benefits are secondary to wind. A bright sunny day with no breeze will always be outperformed by an overcast breezy day at the same temperature. Sun also fades coloured fabrics over time if they are left out for many hours — hang colours inside out in strong sunshine.
Relative humidity is the percentage of water vapour the air currently holds relative to its maximum capacity at that temperature. Higher humidity = less capacity for the air to absorb more moisture from your washing.
UK humidity varies significantly by season and time of day. Early mornings are typically the most humid (often 80–90%), as temperatures are at their overnight minimum and air has less capacity. Humidity typically drops to its daily minimum around 2–4pm on sunny days. This is why afternoon is usually the best time to hang washing — humidity has dropped and there is still good drying time before the evening dew begins to reverse the process.
Getting washing wet with rain after you have hung it out is one of the most frustrating laundry outcomes. The key is understanding how to read rain probability forecasts and what they actually mean.
A 30% rain probability does not mean it will rain for 30% of the day. It means there is a 30% chance that measurable rain (0.1mm or more) will fall at some point during the forecast period at your location. On UK weather apps, this is typically shown per hour. A 20% per-hour probability over a 5-hour period accumulates to a meaningful chance of getting caught — roughly 1 in 1.5 chance something will fall. For washing, treat any hour with above 30% probability as uncertain and plan to bring it in before then.
UK summer produces many days with isolated showers — sunshine punctuated by brief, sharp downpours. These days can be frustrating for line-drying because the showers are often short (10–20 minutes) but heavy enough to thoroughly re-wet washing. If the hourly forecast shows scattered shower risk throughout the day, it is often better to dry indoors on a rack positioned near an open window, rather than repeatedly running out to bring washing in and rehang it.
Do not leave washing out overnight, even if it seems dry. As temperatures fall after sunset, relative humidity rises rapidly — often to 85–95% by midnight. At these humidity levels, dry clothing begins to re-absorb moisture from the air, particularly in still conditions. By morning, clothes that were dry the previous afternoon can feel noticeably damp again. Always bring washing in before sunset, or at the latest by 7pm in summer.
UK winter (November to February) is the hardest period for outdoor drying. Short days, low temperatures, high humidity and frequent rain create conditions where hanging washing outside is rarely worth it.
In December and January, daylight hours in much of the UK are 7–8 hours. Even if you hang washing out at 9am on a dry day, the combination of low sun angle (reduced warming effect), high humidity (often 70–80% even on dry days) and cool temperatures means a typical cotton load may still be damp by the time you need to bring it in at 3–4pm. Towels and heavy jeans are almost never reliably dry in winter outdoors.
In winter, the most efficient approach is: hang washing on an indoor airer positioned in a room with good airflow — ideally near a slightly open window or in a heated room. Opening a window by 5cm creates enough airflow to dry clothes significantly faster than a completely sealed room, without losing too much heat. Avoid hanging large amounts of washing in a bedroom — the moisture released by drying clothes significantly raises indoor humidity and can contribute to condensation and mould over time. Utility rooms or kitchens with extractor fans are better choices.
Get an instant verdict for your location — wind, humidity, rain risk and the best time window to hang your washing out.
Check if today's good for hanging washing →