Using Dimmable ballast. Question

Hey RIU.. Quick question. I am using a dimmable 600/400/250 watt ballast (HPS atm) , and am having some problems with heat and ventilation. I am working on getting an exhaust fan to cool my light, but it wont happen for at least 2 weeks. Its been really warm where I live (east coast Canada) and over the past week my room has been getting too hot. I was wondering if it would shock my Lady's at all to drop the ballast down to 250 watts, to reduce heat. They are being flushed, and have no more than two weeks left to go. I know switching down wattage probably wont make them finish as strong, but will it have any other negative effects?

Thanks

It will not shock them much.. Honestly, i live on the east coast Canada also... and if you have a fan pulling air out and putting it somewhere else you shouldent have much of a problem.
I dont even vent outside right now...

But yeah, I'll put it like this... Your 600w bulb puts out 80k lumen's... Dial it down... to 250... just move your bulb closer... alot closer...
You will stress your plants more by having them to work overtime to cool themselves down from the heat than the reduction in light..

Also how hot is too hot? like 30+ Celsius?

Yesterday my room hit 90. Today its supposed to be warmer outside than yesterday..

No, the sun naturally becomes less and less and weaker and weaker as the seasons goes through in nature. Like you said, they might not finish quite as strong as they could have but I don't think you are going to see any serious negative results from doing this. You definitely want to figure out something more viable for the future though.