UHF Ducting & Repeater

Hello again all.

Well thanks for the reply on the last question. It really cleared a lot up for me. Anyway, back to the topic. Last night, from about 8:30pm, I noticed I was picking up so many repeaters from all over the SE of Queensland, and also people being able to transmit their signal over a very large distance. In fact, I met a person in Ballina, in New South Wales! I was so excited, because I've never seen anything like it before. My question about this is for how many nights does ducting last? I know it is not very common, as in it happens all the time, but will it last for more than just last night? Also would this low pressure system that brought so much rain to SE Queensland be the cause of so much ducting?

The last query is quite weird, as I have never heard anything like this before. Last night when the ducting started coming in, the channel 8 Hervey Bay repeater was making the most horrible noise. Everybody that was hearing it from Ocean View or Redcliffe (they're the guys that were complaining about the noise) and it was apparantly blocking their signals. They seemed to think that the repeater was reversing itself somehow, it was transmitting on 38 or something like that, which I thought was impossible for a repeater to do. Then a guy up here in Maryborough suggested it could be the battery is stuffed and becomes low quite easily, so it needs time to charge up. Question is do any of you guys have any suggestions as to what it could be? The noise is of a repetitive high "beeeeeeeeeep" and then it would maybe get lower and time itself out.
Thanks guys.

Adam :)