Yeah, if you had a wetsuit top, that'd prolly be best. Spring suit is ok, but if the wind is blowing a bit, the short sleeve thing makes it still feel a bit chill. But in the great perspective, it's still warmer to wear just trunks right now than the rubber you'll be putting on in 4 months.
I surfed like 4 hours straight last weekend and was barely chilly...you should be fine unless there's a windchill, in which case you'll still be fine, but if you have one of those nifty wetsuit top things, you'd be super comfy.
Just watch the swell, wind and weather charts and pick your spot. No wetsuit yet. Maybe a sharkskin or something on top. Some guys wear shortsleeve full 2ml suits most of the summer. Judge your own chill factor. When it comes to OCM area: theres always a period in October when one day its boardies the next day wetsuit. Have fun!