Should the sentence be - The continual heat made us thirsty. or The continuous heat made us thirsty.

Continuous is better than continual because it means unceasing. Continual implies an intermittent heat.

http://www.thefreedictionary.com/continual

continuous

To determine whether the correct word to use is "continual" or "continuous," we need to understand the difference between the two.

"Continual" means occurring frequently, periodically, or intermittently, with breaks in between. It suggests a repeated action or event that stops and starts repeatedly.

"Continuous" means happening without interruption, unceasing, or constant. It suggests an action or event that happens in an unbroken sequence.

In the context of your sentence, if the heat is described as occurring in periodic intervals or having breaks in between, then the correct word would be "continual." On the other hand, if the heat is described as uninterrupted, without any breaks or intervals, then the correct word to use would be "continuous."

Therefore, to determine the correct word in relation to your intended meaning, you need to consider whether the heat was happening with breaks or periodical intervals (continual) or if it was happening constantly without any gaps or interruptions (continuous).