There is currently a 90% chance of heatwave conditions between 0900 on Monday and 0900 on Friday in parts of England.
Current advice on how to keep safe in the heatwave includes:
-Staying out of the sun
-Keeping your home as cool as possible. Shading windows and shutting them during the day may help
-Opening windows when it is cooler at night
-Making sure to keep drinking fluids
-If there's anybody you know, for example an older person living on their own, who might be at special risk, make sure they know what to do
The amber warning is issued when threshold temperatures for one or more regions have been reached for one day and then the following night, with the forecast for the next day indicates a 90 percent chance of the threshold being met.
This alert acts as an early warning system forewarning of periods of high temperatures, which could potentially affect the health of the public, and this stage requires social and healthcare services to target specific actions at high-risk groups
Although Yorkshire and the Humber remains at a Level 2 warning, along with the Southwest, this health alert could change as the week progresses and potentially be extended.
Yorkshire is expected to see highs of 28/29C towards the end of the week, this being forecast for Thursday (July 26).
Temperatures could soar to more than 34C in some other parts of the country on Wednesday, beating the 33C recorded at Porthmadog in North Wales on June 28.
Forecasters said there is a chance of hitting 34C or 35C, which could put Britons in line for the hottest day since the mercury hit 34.5C at Heathrow on June 21 last year.
The hottest July day on record is 36.7C (98F), which was reached at Heathrow on July 1 2015.
Met Office forecaster Alex Burkill said: "It does look likely it will be at least 33C at some point this week, most likely on Wednesday or Thursday, in the south east and east, London, Essex, Kent, east Anglia and into Lincolnshire - and that would make it the hottest day we have had so far."
Mr Burkill also explains how the current run of fine weather looks set to continue, stating: "It always seems that when the schools break up that is when we get the bad weather, but in this instance that is not the case."
Warm temperatures are expected to continue well into August, with Yorkshire set to see sunny, dry and warm days throughout the summer holidays.