A monthly temperature area chart compares values across months using an SVG rendering with D3 v7. The visualization reads CSV data via `d3.csv` and maps months to a band scale with `d3.scaleBand`, while temperatures are scaled linearly. An area generator (`d3.area`) fills the region beneath the temperature curve in steel blue, and red circles mark each data point. Hovering over a circle triggers a mouseover event that displays a tooltip showing the month and exact temperature in degrees Celsius.