The short answer
What to wear for a marathon depends on the weather between your start and your finish, not the forecast for the start. Wear kit you've tested on long runs, chosen for mid-race. Add a throwaway layer for a cold start, a light shell and gloves for cold rain, and a cap, sunscreen and pale singlet for heat.
Key takeaways
- Dress for the middle of your race, with layers to shed after the start.
- Boston 2018's cold rain sent 2,785 runners to medical care, per the Boston Athletic Association.
- A Comrades runner can start near 5 °C (41 °F) and finish above 22 °C (72 °F).
- Wear nothing new on race day; test it all on a long run.
On this page
- What should you wear for a marathon?
- What should you wear for a marathon in the heat?
- What should you wear for a cold, wet marathon?
- How do you dress for a race that starts cold and finishes warm?
- What did race day bring at four big marathons?
- What should you test before race day?
- Questions runners ask
- Sources and method
Words this guide uses
- Throwaway layer
- An old top, bin bag or space blanket worn in the start pen and dropped once you warm up.
- Feels like at running pace
- How warm or cold the air feels on your skin with the breeze you make by running, plus the wind, sun and humidity.
- ERA5
- The European reanalysis of past weather, hour by hour on a grid of about 31 km (19 miles), from the Copernicus Climate Change Service.
What should you wear for a marathon?
Wear what you've tested on long runs, chosen for the weather mid-race rather than at the start, plus layers to shed, a shell for cold rain or sun protection for heat. That's what to wear for a marathon, in short.
The start is usually the coldest part of a 4- or 5-hour runner's day. For the wider kit picture, see our guide to running weather apps and kit. To see what your own race brought in past years at your finish time, open it in Map your run.
What should you wear for a marathon in the heat?
As little as possible, in pale colours, with a cap, sunglasses and sunscreen. Then slow your pace early: kit can't undo heat stress.
The 2018 London Marathon was the hottest on record: the Met Office measured 24.2 °C (75.6 °F) at St James's Park. In ERA5 reanalysis along the course, a 4-hour runner started at 18.9 °C (66.0 °F), and the feels like in the sun at running pace reached 26.2 °C (79.2 °F).
Boston in 2017 started at 21.1 °C (70.0 °F), and the feels like reached 28.1 °C (82.6 °F).
- Singlet and short shorts in a light, wicking fabric.
- A pale cap or visor, and sunglasses.
- Sunscreen, applied before you dress.
- Precooling, such as an ice vest or ice slurry drink. A 2015 consensus by Racinais and colleagues says it may help sustained running in the heat; test it first.
Heat illness can kill. The ACSM's 2021 consensus calls exertional heatstroke a true medical emergency. Official race flags and medical advice override this guide, which is not medical advice.
What should you wear for a cold, wet marathon?
A light windproof or waterproof shell, gloves, a cap or hat, and wicking layers that don't hold water. Cold rain is what filled Boston's medical tents in 2018.
The 2018 Boston Marathon is the warning. A 4-hour runner started at 3.2 °C (37.8 °F), never met more than 8.0 °C (46.4 °F), and ran through about 12.4 mm (0.49 in) of rain. With the wind and their own pace, the feels like dropped to −3.2 °C (26.2 °F). According to the Boston Athletic Association, 2,785 runners received medical treatment and 91 went to hospital; Boston Magazine reported the weather caused about 95% of the treatments.
- A light shell, or a bin bag you keep on longer.
- Gloves you don't mind soaking.
- A cap to keep rain out of your eyes.
- Arm warmers or a long-sleeve base layer under a singlet.
- Dry clothes at the finish. You cool fast once you stop.
How do you dress for a race that starts cold and finishes warm?
In layers you can drop or roll down without stopping: a throwaway top, arm warmers, gloves. Dress for the warm finish, and borrow warmth for the cold start.
South Africa's Comrades Marathon shows it sharpest: it starts at 05:30, and runners are out for up to 12 hours. On the 2016 down run, an 11-hour finisher started at 7.1 °C (44.8 °F) and met 26.1 °C (79.0 °F) later. Their feels like ranged from 5.4 °C (41.7 °F) to 28.3 °C (82.9 °F). In 2023, the start was 4.9 °C (40.8 °F) and the day reached 22.1 °C (71.8 °F).
Big-city marathons do it too. At the 2021 Berlin Marathon in Germany, a 4-hour runner started at 16.5 °C (61.7 °F) and met 23.4 °C (74.1 °F).
What did race day bring at four big marathons?
Anything from near-freezing rain to summer heat, sometimes in the same city. Here's a 4-hour marathoner and an 11-hour Comrades runner on seven contrasting race days.
| Race and date | Finish time (h:mm) | Start air, °C (°F) | Warmest air, °C (°F) | Feels like at pace, coldest to hottest, °C (°F) | Rain, mm (in) |
|---|---|---|---|---|---|
| Boston, 16 Apr 2018 | 4:00 | 3.2 (38) | 8.0 (46) | −3.2 to 2.9 (26 to 37) | 12.4 (0.49) |
| London, 24 Apr 2016 | 4:00 | 5.8 (42) | 9.2 (49) | 1.4 to 6.7 (35 to 44) | 0.1 (0.004) |
| Berlin, 26 Sep 2021 | 4:00 | 16.5 (62) | 23.4 (74) | 16.5 to 27.9 (62 to 82) | 0 (0) |
| London, 22 Apr 2018 | 4:00 | 18.9 (66) | 21.6 (71) | 18.9 to 26.2 (66 to 79) | 0 (0) |
| Boston, 17 Apr 2017 | 4:00 | 21.1 (70) | 22.9 (73) | 21.8 to 28.1 (71 to 83) | 0 (0) |
| Comrades (down), 29 May 2016 | 11:00 | 7.1 (45) | 26.1 (79) | 5.4 to 28.3 (42 to 83) | 0 (0) |
| Comrades (down), 11 Jun 2023 | 11:00 | 4.9 (41) | 22.1 (72) | 2.9 to 25.9 (37 to 79) | 0 (0) |
These figures are reanalysis, not a thermometer at the start line. 2015–2024 holds nine race days for Boston, London and Berlin (no 2020 races) and eight for Comrades (none in 2020 or 2021). Boston 2021 and London 2021 and 2022 ran in October, and Comrades 2022 on 28 August. Our marathon weather history hub has every year.
What should you test before race day?
Everything you'll wear, on a long run at your race start time. Nothing new on race day.
- Run 25–30 km (16–19 miles) in the full outfit, at goal pace for part of it.
- Check for rubbing at seams, straps and your race number's pins; use anti-chafe balm where it rubs.
- Rehearse your cold-start and hot-day plans: the throwaway layer, the gloves, the cap.
- Check the forecast at your pace in race week, then pick the outfit two days out.
For temperature-by-temperature kit, use our chart of what to wear running at every temperature.
Questions runners ask
Should I wear a bin bag at the start of a marathon?
On a cold or wet morning, a bin bag with holes for your head and arms keeps you warm and dry in the start pen for almost nothing. Drop it before the line, or soon after, where it won't trip the runners behind you. An old top or space blanket does the same job. Check your race's rules on discarded clothing.
Are arm warmers worth it for a marathon?
Yes, when the race starts cool and warms up. Arm warmers turn a singlet into a long-sleeve top for the first hours, then roll down to your wrists or come off without stopping. They suit races like Comrades, where the 2023 down run started at 4.9 °C (40.8 °F) and reached 22.1 °C (71.8 °F) for an 11-hour finisher.
Is a rain jacket worth wearing in a marathon?
In cold rain, yes: a very light, packable shell keeps wind and water off for hours. In warm rain it's usually too hot, and a cap to keep water off your face is enough. If you do wear one, test it on a long run. A jacket that flaps, rubs or traps sweat for four hours is worse than none.
What should I wear for a marathon at 10 °C (50 °F)?
Shorts and a singlet or T-shirt suit most runners at 10 °C (50 °F), with a throwaway top for the start and perhaps light gloves. Slower runners, who are out longer, often add arm warmers or a thin long-sleeve top. If rain or wind is forecast, carry a light shell.
What should I leave in my marathon kit bag for the finish?
Dry, warm clothes from top to toe, including socks, a hat and a warm layer, plus something to eat and drink. Even on a mild day you can get cold quickly once you stop, and after a cold, wet race it matters most. Add a bag for wet kit and plasters for blisters.
Your race, at your pace.
Pick Comrades, Berlin, London or Boston, set your finish time, and see the heat stress, feels like and dew point you’d have met at every landmark, on every race day from 2015 to 2024.
Sources and method
- Boston Magazine (2018). Thousands of athletes received medical attention at the 2018 Boston Marathon
- Met Office (2025). London Marathon 2025: weather, records and event milestones
- Medicine & Science in Sports & Exercise (ACSM) (2007). American College of Sports Medicine position stand: exertional heat illness during training and competition (Armstrong et al.)
- Current Sports Medicine Reports (ACSM) (2021). ACSM expert consensus statement on exertional heat illness: recognition, management, and return to activity (Roberts et al.)
- British Journal of Sports Medicine (via PMC) (2015). Consensus recommendations on training and competing in the heat (Racinais et al.)
- Copernicus Climate Change Service (ECMWF) (2026). ERA5 hourly data on single levels from 1940 to present
- Quarterly Journal of the Royal Meteorological Society (2020). The ERA5 global reanalysis (Hersbach et al.)
Race-day figures come from RunFast's race-history data (content/blog/data/race-history.json): ERA5 hourly reanalysis (Copernicus Climate Change Service) at grid points along each course, on each real race date and start time, worked out with RunFast's engine for a runner at an even pace finishing in the stated time (4:00 for the marathons, 11:00 for Comrades). Start air is the first kilometre; warmest air and the feels like range are across the whole race at that runner's pace; rain is the total the runner would meet, in mm (inches). Feels like at running pace uses wind chill at the runner's airflow when cool and Steadman's apparent temperature with sun when warm. 2015–2024 covers nine race days for Boston, London and Berlin (no 2020 race) and eight for Comrades (none in 2020 or 2021). Boston 2021 (11 October), London 2021 (3 October) and 2022 (2 October) were autumn races, and Comrades 2022 ran on 28 August. Fahrenheit and inches are our conversions.
Wes Thomson
Wes Thomson builds RunFast, which times the heat, humidity and dew point to a runner's own pace along the route, and its sister Windline, live wind forecasts for cyclists. Both run on the same forecast engine. He writes these guides with one focus: what the weather will do to your run, kilometre by kilometre, and how to plan around it.