Plot.plot({
height: 300,
color: {
type: "threshold",
domain: [-10, 0, 10, 20, 30],
scheme: "cool",
reverse: true,
legend: true
},
y: { domain: [-10, 20], ticks: 0, label: "" },
x: { ticks: 0, label: "" },
facet: { data: davg, y: "month", label: "" },
marks: [Plot.cell(davg, { x: "day", fill: "temp_c" })]
})