From Jurong to Marina Bay, homes, offices and other buildings will go dark tonight to mark Earth Hour, a worldwide movement to raise awareness of climate change.
Singapore first observed this World Wildlife Fund (WWF) initiative in 2009, and participation has grown over the years.
About 9,000 people took part in WWF's Earth Hour celebrations in 2014, up from 6,000 in 2012.
Last year, events were cancelled or scaled down as a mark of respect for late founding Prime Minister Lee Kuan Yew.
Nonetheless, the WWF reached 13,710 people through a Climate Change Trail at Orchard Road.
"In the past few years, Singaporeans have started to experience the effects of the environmental problems we face," said WWF-Singapore communications director Kim Stengert, citing last year's record temperatures and severe haze.
I think Earth Hour has an impact as it does give people a feel of what life will be like, should the world run out of energy.
STUDENT PHUA ZAI JIE
Singapore Environment Council executive director Edwin Seah agreed that green issues have risen in visibility in recent years.
"With the haze crisis last year, the climate change deal reached in Paris last December and rising temperatures, the environment has been constantly in the news with more individuals and corporations coming forward to support programmes aimed at preserving and protecting the environment," he said.
Earth Hour is officially from 8.30pm to 9.30pm, but many events this year begin earlier in the evening, including the WWF's main event at The Float @ Marina Bay.
At 6pm, members of the public can join a bid to break the world record for the largest "human forest", by standing on one leg in a yoga pose known as the tree.
This is in line with the focus of this year's Earth Hour in Singapore: protecting peatland forests, the burning of which causes haze.
Also going dark are commercial buildings such as CapitaLand's malls and the Pan Pacific Singapore hotel, which is encouraging guests to reduce their use of energy too.
Elsewhere, grassroots organisations in West Coast, Hong Kah North and Jurong Spring are holding eco-friendly carnivals.
FairPrice supermarkets and offices will switch off non-essential lights from 8.30pm. FairPrice is also donating $12,500 to the WWF, partly from the sale of eco-friendly reusable bags.
At the LEO foreign worker dormitory in Kaki Bukit, workers will hold a candlelight vigil - an idea proposed by the workers themselves.
Earth Hour is being observed online too. With the Donate Your Social Power app, Facebook users can share information about the effects of climate change.
Mr Seah said: "Earth Hour has done much to raise awareness about the importance of individual contribution towards environmental sustainability."
Student Phua Zai Jie, 21, agreed. "I think Earth Hour has an impact as it does give people a feel of what life will be like should the world run out of energy," he said.
But civil servant Peh Ming Hui, 25, hoped efforts could go further.
"I understand the idea of conservation that Earth Hour is trying to promote, but I feel that switching off lights for an hour doesn't bring across the message strongly enough," he said.
"People should learn to incorporate environmentally friendly habits into their lives on a daily basis."