Almost 1000 schools around New South Wales will have new air conditioning units installed under a $500 million program launched by the state government.

In the past, only schools where the average maximum January temperature exceeded 33 degrees could access air conditioning.

As part of the Cooler Classrooms program, that threshold has dropped to 30 degrees – allowing hundreds of schools to apply for new units.

A new $500 million NSW Government program will provide almost 1000 schools around the state with air conditioning units. (AAP)

“We’re thrilled to be delivering on our commitment to provide healthy learning environments in which our students and teachers can thrive, no matter the weather,” NSW Premier Gladys Berejiklian said.

“From Tumbarumba to Mullumbimby, Bathurst South to Cecil Hills, students and teachers around NSW will benefit from new air conditioning in their school.”

Among the first to receive the new air conditioning units will be Randwick Public School, Engadine West Public School, Cecil Hills High, Parramatta East Public, Mount Druitt Public and Canterbury Girls High School.

Some of the first schools to receive the units include Randwick Public School, Parramatta East Public School and Mount Druitt Public School. (9NEWS)

Casula High School student Christina Krstenska told 9News the installation of the units is desperately needed.

“It does get really tough for students because in classrooms we don’t have the air-conditioning and it’s hard to concentrate,” she said.

“It can get very unbearable. We do have fans in some of the classrooms, but it just circulates the room temperature,” another student, Aira Sagana, said.

In the past, schools where the average maximum January temperature was above 33 could access air conditioning - that has now been changed to an average maximum of 30. (9NEWS)

The installations are expected to take some time, however, with many schools needing to deal with ageing electrical systems that need to be upgraded before the air-conditioning can be added.

The installation process is set to begin over the upcoming summer school holidays.