The 29th annual Hayes Valley Holiday Block Party takes place tonight. But for the first time, the Hayes Valley Neighborhood Association (HVNA) is raising the stakes with a shop window decorating contest.

"We wanted to kick up the holiday block party this year with some friendly competition among the merchants," recording secretary and block party co-chair Jennifer Laska.

Merchants have responded with some impressive decorations: carousels, snowmen, and a mailbox that will really send letters to Santa (in the form of the shop's owner).

The neighborhood as a whole is stepping up, too — this is the first year in a long time that the trees along Hayes Street have been lit with white lights.

For tonight's block party, merchants along Hayes, Octavia, Laguna and Gough streets will stay open until 9 p.m. Many will offer live music, drinks and snacks. Along Hayes Street, expect wandering carolers, drag performers and musicians, as well as live music at Proxy, and a kids' hour.

Tonight's forecast calls for showers, but the party will go on rain or shine. "If it rains, we’ll move the entertainment and kids' activities into some of the stores," Laska said.

In the meantime, here's a look at some of the festive shop windows you can expect to see.

[Update 12/9]: F. Dorian won first place with TV music boxes, a Ferris wheel and carousels in the shop windows. Siren, with an underwater-themed window decoration, received an honorable mention.

The shop window at Fiddlesticks. Owner Elizabeth Leu said all letters dropped off by December 15 with a legible return address will receive a response from Santa.

Decorative lights at Urban Ritual.

Colorful holiday lights at Aiken.

Macaron shop Chantal Guillon offers a sweet side of the holidays.

The holiday lights at Siren's Hayes Valley boutique.

F. Dorian's elaborate display features TV music boxes, a Ferris wheel and carousels.

More details from F. Dorian's window – including some artificial snow.

Arden Home built two snowmen.

Amour Vert has lots of greenery in its windows.