The Army says it will monitor weather conditions closely and will not be using grenades or any other high explosives at the range until fire conditions have "significantly reduced''.
"The safety of our neighbours as well as our own personnel is vitally important to us,'' the letter says.
"The decision not to resume grenade training at this time but recommence ordinary rifle training is a balanced response.
"This will allow NZ Army soldiers to continue to train and prepare for their operational commitments.''
Five houses near West Melton Airport were evacuated and nearby property owners were told to prepare to leave after the fire broke out around noon.
It made its way onto a neighbouring pig farm and 50 hectares were affected.
Incident controller Sergeant Greg Fagg said they had taken measures to prevent a fire from starting, but the blaze had done "exactly what it shouldn't have done''.
