On my journey this morning, I realised that I could to some extent anticipate the arrival of a sudden gust. On the canal it was easy as you can see the water rippling darkly as the wind approaches. On the roads you can do it a bit too.
Look for "tells" - the trees and bushes suddenly coming to life. Pedestrians nearby being blown suddenly, umbrellas exploding inside out. Puddles can give clues - they'll ripple too as the wind gets close.
How to cope ...
The key thing is to use the warning to take evasive action. I don't necessarily mean avoiding the gust, but making sure you've got plenty of room on the road around you. This is because if you do actually get blown to one side, it won't be too dangerous as you are in space, not right next to a car.
Also - remember that you can actually stop! A lot of cyclists seem to think it's beneath their pride to stop and wait for a bit - but if the wind is horrendous and the traffic is terrible, why not pull over and wait for a bit - or walk along the pavement and take a quieter route?
I suspect that if you're clever you can chose roads where you know the wind will be consistent rather than gusty - e.g. a long thin corridor type road. But I'm not that clever.
Generally, when the weather's like this, I would go for the smaller roads where possible and be even more careful about giving yourself plenty of time - and plenty of room from other vehicles.
If all else fails. attach a sail to your bike:
|I blogged about sail bikes|
in Sept last year ...