A British summer is not a season so much as a series of unrelated weather events happening in June, July and August. Twenty-nine degrees on Tuesday, fourteen and horizontal rain on Wednesday, and a thunderstorm on Thursday that floods a road you drive down every day.
Dressing for it is genuinely harder than dressing for winter, because in winter you can simply put more on. In summer the failure modes run in both directions: too hot and you are uncomfortable and burnt, too optimistic and you are cold and soaked.
UV is the bit people get wrong
The most common summer mistake in Britain has nothing to do with temperature. It is assuming that a cloudy, mild day means low UV. It does not. UV is driven by the sun's angle and the thinness of the cloud, not by how warm it feels, and a bright overcast day in June can carry meaningful UV while feeling like eighteen degrees.
The UV index was developed by the World Health Organization and runs across five categories: Low, Moderate, High, Very High and Extreme. The threshold that matters is 3. At UV index 3 or above there is an increased risk of skin damage and protection is advised.
| UV index | What to do |
|---|---|
| 0 to 2, Low | No protection needed for most people. You can safely be outside. |
| 3 to 7, Moderate to High | Seek shade during the middle of the day. Cover up, wear a hat, use sunscreen. |
| 8 and above, Very High to Extreme | Avoid being outside in the middle of the day. Shade, covering clothing, hat and sunscreen are all necessary. |
UK values rarely reach the top of that scale, but a clear day in late June in the south can comfortably sit at 7 or 8, which is a level plenty of people would associate with a holiday abroad rather than with Kent.
What the NHS actually advises
The NHS is specific, and its advice is worth following exactly rather than approximately.
- The sun is strongest in the UK between 11am and 3pm, from March to October. Note that March, not June.
- Use sunscreen with at least SPF 30 and at least 4-star UVA protection. Five stars is the maximum available in the UK.
- Adults should apply around 6 to 8 teaspoons for full body coverage. Applying it thinly significantly reduces the protection you get.
- Reapply every 2 hours, and immediately after swimming or sweating.
- Spend time in the shade between 11am and 3pm, and wear a wide-brimmed hat that shades the face, neck and ears, long sleeves, and close-weave fabrics.
- Children under 6 months should be kept out of direct strong sunlight. Older children need at least SPF 30 from March to October, plus shade and clothing.
The clothing point is the one that gets ignored. A close-weave long-sleeved shirt does more, more reliably, than sunscreen you applied at nine in the morning and forgot about. It never needs reapplying and you cannot miss a bit.
Dressing for heat: cover up, do not strip off
The instinct in hot weather is to wear as little as possible. In direct sun that is often the wrong call, because bare skin is absorbing solar radiation while covered skin is not.
What works:
- Loose, not tight. Air moving between fabric and skin is what carries heat away. A tight synthetic top traps it.
- Natural or technical fibres. Linen and cotton are comfortable in still air. Technical synthetics move sweat better when you are actually exerting yourself.
- Light colours in direct sun, because they reflect more.
- A brimmed hat rather than a cap. A cap leaves your ears and the back of your neck exposed, which is where a great many people burn.
- Sunglasses with UV protection. Look for the CE or UKCA mark and UV400.
- Sandals or shoes you can actually walk in. Feet swell in heat, and a shoe that fits at 8am can be unbearable by 4pm.
The classic British burn is the tops of the feet, in sandals, on the first properly hot day. Nobody puts sunscreen there.
Heat-Health Alerts
In a genuinely hot spell, two separate things may be issued. The Met Office may issue an extreme heat warning, which is about impacts from the weather. The UK Health Security Agency, working with the Met Office, may issue a Heat-Health Alert, which is about expected effects on health and health services. Its core season runs from 1 June to 30 September.
You can have one without the other, and the health alert is the one to watch if you are responsible for someone elderly or with a health condition. Sustained warm nights are hard on people even when the daytime peak is not remarkable.
Worth knowing the NHS signs of heat exhaustion: tiredness, dizziness, headache, feeling or being sick, excessive sweating, skin becoming pale and clammy, cramps in the arms, legs and stomach, a high temperature, being very thirsty, feeling irritable. Move the person somewhere cool, remove unnecessary clothing, give them plenty of water and cool their skin. If they are still unwell after 30 minutes of resting in a cool place, or show signs of heatstroke such as a very high temperature, hot skin that is not sweating, confusion, a seizure or loss of consciousness, call 999.
The downpour problem
The other half of a British summer is the summer storm. Convective rain in July arrives fast and heavily, and it is not the sort of thing a light shower jacket copes with.
The practical answer is a packable waterproof that lives in your bag from June to September and never comes out otherwise. Something around 5,000 to 10,000mm hydrostatic head, weighing very little, with a hood. You will not wear it most days, and on the days you need it you will need it badly.
Two more things worth carrying in summer specifically:
- A thin layer for the evening. A 26 degree afternoon can become a 13 degree evening, and people dressed for the afternoon are cold by nine.
- Shoes you do not mind soaking. Summer downpours produce standing water on pavements far faster than winter drizzle does.
A worked day
Forecast: 24 degrees, UV index 6, 40% chance of a thunderstorm from 4pm, dropping to 14 degrees overnight.
Loose long-sleeved cotton or linen shirt, light trousers or a skirt, brimmed hat, sunglasses, SPF 30 or higher on face, neck, ears, hands and any exposed skin, reapplied at lunchtime. Shade between 11 and 3. A packable waterproof and a thin layer in the bag. Shoes rather than sandals if you are out past six.
That is one outfit and two small items in a bag, and it covers the entire range that day can throw at you. Which is the whole trick to a British summer: dress for the middle of the forecast and carry the edges.
The outfit tool reads today's actual forecast rather than the season, and the guide to dressing for UK weather covers the underlying principles year round.