Ice detection systems for aircraft and related methods are disclosed. A disclosed example ice detection system includes a thermochromic device to sense a temperature of freestream air relative to a temperature threshold, and a hydrochromic device to sense an amount of moisture in the freestream air relative to a moisture threshold. A controller to detect an icing condition in response to the thermochromic device sensing a temperature that is less than or equal to the temperature threshold and the hydrochromic device sensing an amount moisture that exceeds the moisture threshold.