Always keep in mind we have very unpredictable weather here and can often get 4 seasons in one day (it's best to embrace it).
To get a gauge on what the waves might be like in Thurso, have a look at Surf Line. It will show you the tide, swell size, swell direction, wind speed and direction for up to a week. Depending on what spot your wanting to surf, depends on what conditions your after. We find the best thing to do is look at a map so you can see what angles the beaches face. This will help you determine which direction of swell and wind is required for good waves. Get in touch if you have any questions!