We study the effect of weather shocks on legal and illegal migration from rural Mexico to the US. First, we find that shocks in the wet season on precipitation and temperature increase migration. The increment is entirely driven by illegal migrants. Second, we propose a mechanism to explain this result: the effect of weather on agricultural production. We find that shocks on precipitation and temperature decrease total harvested land and corn production. Third, we show that young and unwealthy workers are more sensitive to weather shocks. Lastly, we use climate projections to have a first glance on the impact that climate change will have on migration. We find that a shift of the size of climate change would double the number of illegal migrants. Since climate change will increase the frequency and intensity of weather shocks, our findings are increasingly relevant.