I have open deck sitting area. How to make warm and cosy for fall ?

Here are lots of great fall porch/deck fall decorations:

https://www.hometalk.com/search/all?filter=fall%20porch

Here's a post that might help - https://happyhappynester.com/how-to-create-a-cozy-outdoor-living-space/

Add a deck safe fire pit or make one of these: https://www.diyncrafts.com/25220/decor/15-diy-patio-fire-bowls-will-make-summer-evenings-relaxing-fun

Add some cozy throws to the chairs to snuggle beneath, and some fall pillows.

Hello. You might find some ideas at this link.

https://my100yearoldhome.com/fall-porch-decor-ideas/

Have you thought about searching the visuals on Pinterest or Houzz for inspiration? There is a wealth of ideas and visual inspiration there for your consideration. That might lead you to decide on an idea or theme. After that I’ll be assembling materials and starting your decorating project

Use a bale of hay to make a fall decoration setting. Put fall flowers on the ground with pumpkins and gourds and flowers on top of it. Put a table in the middle of seating with flameless candles.

Fire pit would be a great addition. Some outdoor pumpkins for fall decor. Candles or torches fir lighting. Carry blankets out when you are going to be seated around.

Have you considered an out door heater or Tiki torches. Decorate with fall items to mark the season.

Here's an article that will give you several great ideas. Cozy up! :)

https://www.gnhlumber.com/make-your-deck-cozy-gathering-place-fall/

Joane: I have one of these -- I love it!

https://www.amazon.com/s?k=table+top+fireplace&ref=nb_sb_noss_2

Can you add a propane fire pit? That would make it so cozy!

Hi Joanne, you could add some pillows and throws to area. Seating cushions to match. Have fun and enjoy fall

Throw or area rugs.

Pillows or bean bag chairs.

A hammock.

Lightening.

Benches (padded for extra comfort).

They have outdoor speakers so you can pipe music outside.

Solar rope lights.

A wind chime (ones that are tuned sound much better).

If the area is open does that mean no roof or walls?

We have a pergola that helps keep some of the sun off us and a 2 seater chair and then twin chairs around a table. I have a rug and then I bring out pillows and blankets when we're out there. You could look for a portable or tabletop fire pit. Pot some mums and ferns, to add some nature to the porch. :)

I use a chimanea for my open deck area https://amzn.to/338y2bU

Do you have a fire pit?

Hello Joane, hope this link helps you out,

https://heattrak.com/blogs/homeowner/five-ways-to-heat-your-deck-this-winter

Adding green plants or small potted trees are one way to spruce up your area

and of course seasonal colors too

https://www.hometalk.com/diy/build/fire-pits/table-top-fire-pit-44256473

https://www.hometalk.com/diy/outdoor/furniture/fire-pit-table-top-481193