Ralph Thoresby School made the announcement on Twitter after sending a letter to parents.
Pupils have been encouraged to work from home after 12.10pm on each day by the secondary school in Holt Park.
In the social media post, the school said: "Due to the extreme weather forecast for Mon / Tues, we are encouraging students to work online from home after 12.10pm.
"Full details are in the letter sent to all families earlier today.
"We are prioritising student safety in the these unprecedented conditions.
Level four comes with a warning that illness and death may occur among the fit and healthy.
Leeds is also among the cities to have been issued a red warning by the Met Office for Monday July 18 and Tuesday July 19.
The Met Office have warned of the exceptionally hot spell 'leading to widespread impacts on people and infrastructure'.
People have been told to expect adverse health effects not limited to those vulnerable to extreme heat, a high risk of heat-sensitive systems and equipment failure, as well as delays and closures on roads.
Met Office spokesman Grahame Madge said: “If people have vulnerable relatives or neighbours, now is the time to make sure they’re putting suitable measures in place to be able to cope with the heat because if the forecast is as we think it will be in the red warning area, then people’s lives are at risk.
“This is a very serious situation.”