Dom Joly: Blue-sky thinking spoiled by a powerful tornado

The weather has become a constant source of debate here in the last week of my Canadian Lakes holiday. We arrived in Toronto about three weeks ago on the back of a July heatwave that had everybody talking – "One day it was 47 degrees centigrade... well, not actually... but that's what it felt like." Canadian weather forecasters tell you the exact temperature but then adjust it for the humidity to tell you what it "feels like".

This seems to be a fairly unscientific approach to meteorology. I know little about the world of weather, but can Ontario, with no tricky mountain ranges and an essentially flat landscape, really be that difficult to forecast? I must be mistaken because the daily predictions are so wrong it has become laughable. We check a variety of weather outlets online. Some cheerily predict blue sky and sun while others gloomily predict clouds and rain.

We have settled on one website as it is the most incorrect of all. For the last week we have formulated our plans by assuming the weather will be the opposite of whatever it predicts. It has been spot on/off every day, and this made up my mind: when I retire I'm going to buy a cottage on the Muskoka lakes, my favourite place in the world, and spend my final days as a weather forecaster.

I'm going to have it all set up just the way I want it. I shall be in my hammock, on the dock, rocking gently over the velvety, soft waters. Every day, at a pre-assigned time I shall drop a peanut on to the dock. A chipmunk will appear as from nowhere and snaffle said peanut. If he runs away to the left of my hammock, it will be "Scorchio"; if he goes to the right, then I'm afraid it's "Rain ahoy". I see no reason why this system would be any less effective than whatever method our local forecaster uses.

Yesterday, he excelled himself with a "tornado warning" over Muskoka. We howled with laughter at this and started naming the "tornado" as we gaily set off on a full day's expedition in the boat: "Doofus, Bonehead and Old Yella" were the favourites.

We visited a little remote island in Lake Joseph where we did some cliff-jumping before going over to Bala on Lake Muskoka for some knee-boarding and lunch. The day was perfect and, as we pootled home through the locks at Port Carling, we remarked that the world needed more Canadian tornadoes as they were remarkably pleasant. We ended an idyllic day with some night swimming and a game of Balderdash.

The following morning, after being assured by our favourite weather forecaster that it was going to rain, we set off on another boat trip. As we rounded a nearby island, we came across an extraordinary sight: something had hit the shore with unbelievable force and cut a clean path across it. One cottage had its roof caved in by three enormous pine trees. A floating flock of rubber-neckers were already in situ, oohing and aahing over the destruction. I manoeuvred the boat next to another and asked them what happened?

"It was a tornado," said one man. "It just came out of nowhere and ripped the place apart. Luckily nobody was home, but it's made a real mess." I was going to point out that it hardly came out of nowhere since there had been a tornado warning yesterday, but then I realised that they placed as much credibility in them as we did.

We're supposed to be heading off to a farmer's market on the boat today, but the weather forecast is for blue skies and sun... what to do?