Getty imagesHeat Health Alert is all over England till 18:00 BST on Wednesday.
Amber warning has been issued for Eastern Midlands, West Midlands, East England, London and Southeast.
There is less severe yellow warnings for the North East, North West, Yorkshire and Hamber and South West.
Alerts warn the public when high temperature creates a possible risk for health.
How does the weather health warning system work?
Weather alert service is run by UK Health Security Agency (UKHSA) and Met Office.
This includes both heat health and cold health alert.
Heat health alerts are issued between 1 June and 30 September, and cold health alerts are published between November 1 to March 30.
Along with warning the public, the system directly sends guidance to NHS England, government and healthcare professionals during adverse weather periods.
The alert is classified according to severity and includes:
- Weather situation is expected in the coming days
- Description of how the weather conditions will affect each area
- Link for additional information, advice and guidance
The system was designed to help reduce the disease and deaths during the period of extremely hot and cold weather.
What does alert level mean?
The level of alert is based on Mate Office Forecast and Data.
There are four levels from green (at least severe) to red (most serious):
Green
Green is the normal level of green, when it is advisable how people should prepare to respond to an increase or fall in temperature.
Yellow
Yellow alerts are released during hot or cold weather periods that are only likely to affect people who are particularly weak, for example people with elderly, or existing health conditions.
Sky
Amber alerts are released in conditions that may potentially risk the entire population. For example, NHS may see an increased demand on GPS and ambulances.
Travel disruption is also likely.
Red
A red warning is the most serious.
This is released in situations when hot or cold weather will be a significant risk for life, even for healthy population, and can lead to the failures of the important national infrastructure, such as power outage or roads and rail lines can be discontinued.
What does hot weather do the body?
As the body gets hot, blood vessels opens. It reduces blood pressure, and the heart works hard to push the blood around the body.
It can cause mild symptoms such as itchy heat or swollen legs, as the blood vessels are dripped.
At the same time, sweat causes loss of fluid and salt and, significantly, the balance in the body changes.
This may be combined with low blood pressure, Tiredness and Heatstroke SummerSymptoms include:
- Dizziness
- nausea
- Fainting
- Confusion
- muscle cramps
- Headache
- Heavy sweat
- Tiredness
If the blood pressure goes away significantly, the risk of heart attack increases.
