There's an amber heat health alert Tuesday to Friday in my neck of the woods.
Advice: https://www.gov.uk/government/publications/beat-the-heat-hot-weather-advice/beat-the-heat-staying-safe-in-hot-weather
TL;DR: open windows and curtains when it's cool and shut them when it's hot, especially in the sun; drink *lots* of non-alcoholic fluids (more than you think you need to); know the symptoms of heatstroke and who to call if you or someone you know has them; try to only go outside at cooler times of day, and when you do, wear sunscreen and a wide-brimmed hat.
#HeatWave