All access land within the national park will be shut until the risk has reduced.
It comes amid an amber weather warning for extreme heat for much on England on Monday and Tuesday, with temperatures in the area expected to reach 34°C today.
The ban does not affect public footpaths, but visitors who do venture to the park are asked to be careful and pay particular attention to wildfire risks.
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In a statement, the Peak District National Park Authority said: "The risk of fires breaking out on the Peak District Moors has now reached a critical level, unseen for many years. As a result of this, public access has been suspended from all Access Land until this exceptional risk has reduced.”
Access land is indicated by signs and, in some areas, temporary closure signs may also be in place.
The park's statement added: "Whilst the fire risk remains exceptional, Access Land should not be entered until further notice.
"Public footpaths are unaffected by the Access Land closures, but we ask that people are particularly vigilant and take extra care to ensure they don’t risk starting a wild fire.”
Anyone who sees an uncontrolled fire, or large volumes of smoke, in the park should contact emergency services.
The park authority anticipates all its visitor and cycle hire centres will remain open and operational, but this could change at short notice.
Food, drinks and refreshment concessions may also be affected by the extreme weather.