The Weather conditions on the South Downs Way are not susceptible to massive fluctuations but it is worth knowing what to expect before heading out for a day or two walking or cycling the trail. The South Downs Way National Trail isn’t high altitude or especially remote, but it does reach almost 250m at a couple of points. Butser Hill, Hampshire 270m (900ft) / Ditchling Beacon, East Sussex 248m (814ft). In both locations the Trail runs just below the summits at 245m and therefore both can claim to be the highest points.
Having said this, it is still susceptible to the elements, especially on the higher points, and a good wind can blow in from the sea to really blow through you.
Given the numerous high points along the route and the openess to the elements, as well as the effort required to reach the summits along the way, you should not underestimate the weather conditions which you could encounter.
The prevailing wind is a southwesterly approximately 85% of the time, which means that you have a greater chance of having the wind at your back if you go from West to East rather than vice versa.
The time of year will clearly have an impact on the weather, and we have been walking and cycling on the South Downs Way in snow, hard frost (-15 degrees one boxing day ride at the top of Old Winchester Hill, plus wind chill), driving rain, drizzle, glorious sunshine and baking hot summers days, so be prepared for anything and use a service such as www.bbc.co.uk/weather to help you with understanding what may be coming your way
Even on the warmest day, if you are likely to be up on the ridges very early in the morning or late in the evening or possibly overnight, it can cool down quickly.