Yeah, that's about right. A lot of the reason that the forecast is off at the west end of the lake is due to the fact that the land "pinches" a bit there and there is higher, hotter land acting like a pair of cupped hands from Niagara and the Escarpement all the way to the Oak Ridges Moraine.
The prevailing westerlies/south-westerlies of summer can soar completely over the water before "sinking" halfway to Cobourg. Alternatively, pop-up thunderstorms in humid air (like today) can form fast, nasty squalls. At least you got your timing right, and in a 26' footer, it's better to reef or lash down completely, get the engine going, and plow into it for the 10 minutes until it dies. You'll usually be rewarded with a fresh, clean westerlies to work with on a beam reach.
Anyone racing out of Toronto knows that the wind will die a hour before sunset, as the onshore breeze fails in front of the breeze from the city created by heat "uncorked" into the lake. I sail out of National Yacht Club, and knowing this, you can use that late in the race puff to win if you can creep into position parallel to the shore.
Generally, mid-lake can be dead in the summer if the heat in the surrounding land is send air up instead of across...always bring plenty of fuel or plenty of time, or buy a cruising spinnaker.