Heatwaves and extreme heat events are a threat to human health and infrastructure, and public understanding of those risks plays a major part of climate change adaptation policy. At the same time, extreme heat is a topic of public interest, although how much people's attitudes to—or behaviours around—climate change are affected by information on climate extremes is still an area of active research.

Here, we discuss two websites designed to communicate extreme heat to a broad audience: Scorcher (scorcher.org.au) and Is it Hot Right Now? (isithotrightnow.com). Scorcher presents a nation-wide view of current heatwaves (defined as three or more consecutive days that exceed the 90th percentile of maximum temperature), allowing users to rewind the map back in time or to focus on heatwaves over time at individual high-quality weather stations. In contrast, Is It Hot Right Now? focuses on local conditions, comparing the current day's temperature at ten high-quality stations to the historical range of temperatures for the current time of year, rating the temperature in relative terms.

Despite these differences in approach, Scorcher and Is It Hot Right Now? have both found success as popularly accessible communication tools and are regularly featured on social media, especially during intense heat events and heatwaves.

In this session, we discuss design decisions made both during construction and in subsequent iterations, as well as insights from user feedback and analytics. We also discuss the purposes sites like these can play in shaping public understanding and behavioural change with reference to recent science communication research.