Garden-esque attire. Dresses, Sunday best. For women, wedge heels or flats may be best since the ceremony will be on turf.
Most likely, sunny and 80s during the day, and beginning to cool down to 60s-70s during the ceremony.
Casual Appetizers and Dinner will be provided
Ceremony will be probably around 30 minutes and the reception may be a couple of hours for dancing and dinner