Too cold for an outdoor wedding ceremony

I would just let guests know it's going to be colder than expected and they may want a coat, if it's financially possible you could also provide blankets for the guests.

I think you should just send a note out to guests, send the weather forecast and say there will be a 30 minute (Just in case things run behind!) outdoor ceremony so to dress for the weather. End by saying you are so excited to see everyone!

Make sure you start the heaters about 30 minutes before guests arrive so the area can warm up a bit

If it's cold, Yes. If it's raining or sprinkling, No. I would be miserable sitting in cold, damp clothes for the rest of the night. Hopefully you have a good backup plan for rain!

Do you have any kind of tenting or a contingency plan for if it rains? It sounds like you have the cold covered with the heaters/ hand warmers, but wet clothes, wet hair, and smeared makeup can put a damper on things. Also, is there any kind of cement or similar flooring for guests to walk on? A LOT of women wear heels to weddings, and mud/ soft ground can be a disaster.

45 degrees is cold! Especially if it’s sprinkling rain or damp out. Personally, I would move the wedding inside.

Yay, it’s almost time! That’s not super cold, I wouldn’t stress. A couple suggestions:
1) Have the heaters on in advance to warm the area up a bit.
2) Let guests know today about the upcoming forecast and advise that they bring a coat for the ceremony, as well as an umbrella incase it does drizzle.3) Have umbrellas available for your bridal party and officiant, unless they have their own to bring. 4) HAVE FUN!!
P.S. I’m a teacher and we still go outside for recess when it’s high 20s, 30 minutes outside. It’s chilly at that temp, but standing outside in the 40s is typically comfortable with a coat. If it’s windy, of course it’ll feel chillier, but it’s only a short while.

Yay wedding week!! I would do as the others have said - circulate a message to your guests. We did this week of, as it was set to be cooler than expected. We told people that if they were like the bride (a cold reptile) that it would make sense to bring layers, haha.

Otherwise, whilst it does sound like it will be quite cold, it's fine for 20 minutes. As a guest I'd just wear a coat, wrap up warm with gloves and a scarf, and hustle inside as soon as practicable once the ceremony was done.

I agree with others that a tent is a good idea for rain. If the area isn't paved, you might want to set up the tent the day before if you're allowed. That way the ground won't be too wet.