To find the change in temperature between −20°F and 30°F, we can subtract the lower temperature from the higher temperature:
\[ \Delta T = T_{\text{final}} - T_{\text{initial}} = 30°F - (-20°F) \]
This simplifies to:
\[ \Delta T = 30°F + 20°F = 50°F \]
So, the change in temperature is 50°F.