"The Extreme heat warning... will be in force from Thursday through until the end of Sunday with impacts possible to health, transport and infrastructure," the statement read.
The heat will build through the week, peaking on Friday and Saturday, with temperatures expected to rise into the low-to-mid 30s Celsius (86 degrees Fahrenheit).
Amber is the second highest level of threat on the three-tier scale. It means that there is the possibility of travel delays, road and rail closures, power cuts, and the potential risk to life and property.
The only time the Met Office issued a red warning was in mid-July when new national records were set. The highest ever temperatures of 40.3 degrees C were confirmed at Coningsby in Lincolnshire.