My just-turned-2 toddler is so unhappy. :( The grass and tree pollen is just awful for him this time of year - he had a hard time last year, but we're outside a lot more this year (he's learning to peddle and push a bike, we're swimming, taking walks, all the "normal" outdoor kid stuff for this time of year, and he has an older brother who can't be asked to sit inside all day long just b/c his brother is sniffly) and he's just miserable. His father has allergies, and they are the same symptoms - watery, itchy eyes, clear runny nose and a bit of a scratchy cough. I do NOT want to give him allergy meds if I can avoid it - this doesn't last all year, and meds either make him sleepy or jumpy. Other than keeping him inside all the time in an air-conditioned environment, what can I do to help some of his symptoms?

Benadryl is notorious for making kids jumpy. If you find meds that make him sleepy, you can give them at night.
We've had great luck with claritin which you can get over the counter. C won't take the liquid so we cut the pills for the older kids in half so as to get the right dose.
You are fortunate in knowing when his allergy season is as that way you only have to medicate during that season. You shouldn't have to use the meds year round.
Don't forget to use your air conditioner during this time. Have him shower/bathe before bed so as to get the pollen off of him and not into his bedding.