5 key things to remember ahead of a UK snap heatwave

Heat increases the strain on the body, so it is completely normal for your usual pace to feel more difficult, or for you to run slower than normal. At around 30°C, do not be surprised if your normal pace is up to 15-20% slower for the same effort. For a 5:00/km runner, that could mean closer to ~5:45/km while feeling just as hard. You haven't lost fitness overnight it is the cost of running in the heat. Use effort as your guide rather than chasing the pace you would expect in cooler conditions.

If you do want to get your run done when it feels cooler, aim for early morning or later evening. This is especially useful for harder sessions, longer runs, or if you know you struggle in the heat.

Go for lightweight, breathable clothing that allows sweat to evaporate. Loose-fitting kit can help with airflow, and lighter colours may reduce heat gain from the sun. The key is to avoid heavy, restrictive layers that trap heat and sweat. A cap, sunglasses and sunscreen can also help reduce direct sun exposure.

Start hydrated and keep fluids available across the day. For longer runs, heavy sweat sessions, or back-to-back training days, electrolytes can help replace some of the sodium lost in sweat. Bonus point: plan ahead and get your drinks chilled. Cold fluids can help you feel cooler and may support performance in hot conditions.

Feeling hot, working harder than normal and sweating more are expected in warm weather. But dizziness, chills, nausea, headache, unusual weakness, cramping, poor coordination, or feeling very hot and unwell are warning signs. If that happens, stop the session, get into shade or a cooler place, loosen any tight clothing, sip fluids if you can, and cool yourself down with cold water, a wet towel, or a cold drink. Do not try to “push through” to finish the run. No session is worth risking heat illness. The aim is to train consistently over weeks and months, not force one run in unsafe conditions.