I created a plot with a horizontal BarLegend for TemperatureColors (see1).
Code:
PlotLegends ->
Placed[BarLegend[{"TemperatureMap", {15, 30}},Ticks -> Table[i, {i, 15, 31, 1}], LegendMarkerSize -> 300,
LegendLabel -> "T(\[Degree]C)",
LabelStyle -> {Bold, Black, 11}], {Bottom, Center}]
Now I just want to have the BarLegend having the temperatures on it decreasing from left to right, means values and colors reversed with high temperatures on the left.