Jez once told me he was sailing in Esperance and at a 45 degree angle to his board,a few metres away ......he sees a big shadow coming towards him.........a 4-5 metre GWS.
Was there between Christmas and New Year. Wind was fickle much of the time and missed out on a sail (went sea kayaking instead!). May still be some wind later in March on the south coast. I'm in Albany and we often get sailable E/SE winds right through March and into early April (we get similar weather patterns to Esperance).
Check out Esperance weather observations for March last year: http://www.bom.gov.au/climate/dwo/201403/html/IDCJDW6040.201403.shtml
For slalom/freeride sailing in E/SE wind, suggest you try launching from either of these locations: - Opposite Comfort Inn - Car park at corner of Goldfields Rd & Castletown Quay - Yacht club
As for wave sailing, haven't done any around Esperance but have heard that Observatory Point is the best for DTL sailing whilst Fourth Beach could be worth a try for jumping and mucking around in the surf.