Boost for solar
The leaders, who will only stay at the meeting for one day, are likely to make a number of significant announcements during the day to boost the fight against rising temperatures.
France and India will announce a global alliance that aims to bring together 100 solar-rich countries in tropical regions to rapidly expand the availability of electricity from the Sun.
There are also expected to be announcements on funding for renewable energy research.
But among the warm words and good intentions, there are growing concerns among the very poorest countries that their interests might be sacrificed in the clamour for compromise.
Most of the discussions here will revolve around a new deal that would limit global warming to 2C.
Assessments of the more than 180 national plans that have been submitted by countries suggest that if they were implemented the world would see a rise of nearer to 3C.
However, the 48 members of the least developed countries (LDC) group at these talks say that for them, anything more than 1.5 degrees would be catastrophic.
"For the LDCs, economic development, regional food security, ecosystems, and the very survival of their populations and livelihoods are at risk if talks aim only for a 2C world," said Giza Gaspar Martins from Angola.
"The heads of state will be in Paris to set the tone for the negotiations. We renew our call for an ambitious, robust and binding climate deal that does not leave behind the most vulnerable among us."
While the arrival of the leaders will give a significant boost to the conference, the practical difficulties of securing a deal have not gone away.