This example visualizes daily temperature data from San Francisco as a radial area chart. The circular layout uses time as the angular axis, with months labeled along concentric rings. Two filled bands show the range between average minimum and maximum temperatures, while a wider, lighter band displays the overall span of extreme temperatures. The chart is built with D3's radial scale and line generators, including `d3.scaleUtc()`, `d3.lineRadial()`, `d3.areaRadial()`, and `d3.curveLinearClosed()`. Data is read from a CSV file and aggregated by day of the year using `d3.rollup()`.