Will depend on what Willowbank does. If it gets bad enough that THEY cancel the event it would be either refunded or rescheduled at their discretion. If it's just that YOU don't want to risk it, you pays your money and you take your chances. Same thing happened with the sprint day we ran, they were happy to keep the track open and people continued to run. Some people chose not to go out but as the event was still on that was their choice not to participate. That said, BOM is predicting a fine day with a small possibility of rain with no more than 1mm of precipitation. Expect a cool, clear day with moderate cloud cover