Living with Uncertainty: Climate Change, Informal Work, and Everyday Vulnerability in Tamil Nadu analyses how climate variability and extreme weather events affect the livelihoods, housing, health, and financial security of informal workers across Chennai, Chengalpattu, and Tiruvannamalai districts. Using a mixed-methods approach combining surveys with 166 informal workers and focus group discussions, the study documents how rising temperatures, irregular rainfall, flooding, drought, and heat stress intensify existing socio-economic vulnerabilities. The findings show that informal workers, particularly domestic workers, street vendors, construction labourers, sanitation workers, and daily wage earners, experience recurring income loss, housing damage, health risks, food insecurity, indebtedness, and disruptions to children’s education due to climate-related shocks. The report emphasises the unequal impacts of climate change shaped by caste, gender, migration status, and inadequate access to infrastructure and social protection. It recommends climate-just policy interventions focused on resilient housing, livelihood security, healthcare, financial inclusion, and participatory governance to strengthen long-term resilience among vulnerable urban and peri-urban communities in Tamil Nadu.