Which city shown on the map has the lowest temperature?

• Edinburgh: $6^\circ \text{C}$
• Dublin: $-1^\circ \text{C}$
• York: $9^\circ \text{C}$
• Cardiff: $-8^\circ \text{C}$
• London: $-3^\circ \text{C}$
• Exeter: $-7^\circ \text{C}$

We are looking for the smallest number among $6, -1, 9, -8, -3, -7$.
Negative numbers are always lower than positive numbers.
Comparing the negative temperatures: $-1, -8, -3, -7$.
On a number line, the further a negative number is from zero, the smaller its value.
Therefore, $-8^\circ \text{C}$ is the lowest temperature.

The city with a temperature of $-8^\circ \text{C}$ is Cardiff.

The city with the lowest temperature is $\text{Cardiff}$.