A hot spell will develop across parts of England and Wales later this week. What to expect: Adverse health effects are likely to be experienced by those vulnerable to extreme heat The wider population are likely to experience some adverse health effects including sunburn or heat exhaustion (dehydration, nausea, fatigue) and other heat related illnesses Some changes in working practices and daily routines likely to be required An increased chance that some heat-sensitive systems and equipment may fail. More people are likely to visit coastal areas, lakes, rivers and other beauty spots leading to an increased risk of water safety and fire-related incidents. Some delays to road, rail and air travel are possible, with potential for welfare issues for those who experience prolonged delays Further details: Temperatures will increase across much of the UK over the coming week. Temperatures will be highest across parts of England and Wales with these peaking on Friday and Saturday. In addition to high daytime maxima, temperatures overnight will remain very warm, especially in larger urban areas.