Update: You can also use GetCoordinates
from the right-click menu:
f[v_, t_] := 91.4 + (91.4 - t) (0.023 v - 0.304 Sqrt[v] - 0.474);
ContourPlot[f[v, t], {v, 4, 45}, {t, -60, 30}, ContourLabels -> True]

Use CoordinatesToolOptions to customize the content displayed:
ContourPlot[f[v, t], {v, 4, 45}, {t, -60, 30}, ContourLabels -> True,
CoordinatesToolOptions -> {"DisplayFunction" ->
Function[pt, Row[{"f(", pt[[1]], ",", pt[[2]] ") = ", f @@ pt}]]}]

Original post:
Manipulate[ContourPlot[91.4 + (91.4 - t) (0.023 v - 0.304 Sqrt[v] - 0.474),
{v, 4, 45}, {t, -60, 30},
ContourLabels -> True, PlotLabel -> Style[spot, "Panel", 16]],
{{spot, {30, 15}}, {5, -60}, {45, 25}, Locator}]
or
Manipulate[Labeled[ContourPlot[91.4 + (91.4 - t) (0.023 v - 0.304 Sqrt[v] - 0.474),
{v, 4, 45}, {t, -60, 30}, ContourLabels -> True],
Style[spot, "Panel", 16], Top],
{{spot, {30, 15}}, {5, -60}, {45, 25}, Locator}]
to get
