Here are a few useful links to local weather information:
XCWeather my favourite.
Windguru for Hayling Island giving forecast for wind speed, direction, temperature and wave height for Hayling Island.
Live weather reports from Chichester Harbour entrance: CHIMET
Tides at Southsea Marina including access times
UKHO Tidal Prediction for Portsmouth (7 days)
Download a document showing the tidal streams at each stage of the tide in the Eastern Solent area: Tidal Streams
Water temperatures go from a low of 5 degrees Centigrade in Winter to a high of nearly 20 degrees in Summer. The temperature profile lags behind the air temperature, as water stays warmer for longer which is why the water feels warm well into November and summer species stay on. Here is a chart based in readings taken at midday on the first day of each month in 2010, from the data archives available from the Chichester Bar weather station: