Combine all ingredients in a high speed blender.
Blend until smooth. Serve immediately.
If you don’t have a high speed blender, I recommend that you mince the jalapeno before adding it to the blender to prevent big chunks of jalapeno. I like to taste a little nibble of the jalapeno to see how spicy it is. Sometimes I’ll add a bit more jalapeno if the pepper I have is more mild.
You could also add 1/2 cup of milk of your choice to give add creaminess to this watermelon smoothie. It will also help take off the heat of the jalapeno. I recommend almond milk or soy milk in this watermelon smoothie. If you’re using frozen fruit, you won’t need any ice for this smoothie. Instead of adding ice, try freezing the watermelon ahead of time!