Just let it do its thing. This is perfectly normal, the open circuit volts will just follow wind speed.
When connected to the battery it will just supply an increasing current with wind speed. Until the battery is fully charged and gassing you needn't worry. If you reach gassing volts the battery voltage will then rise excessively, either use more power than you are producing, shut the turbine down or fit a diversion charge controller.
Wind turbines should not be run on open circuit, the speed can be excessive and as you found the volts can get to dangerous levels in high wind.
Flux