Here's Why You Shouldn't Make Matcha With Cold Water - Tasting Table
Briefly

Using cold water to make matcha is possible, but it will take longer to froth with a bamboo whisk. Hot water will enhance the flavor and dissolve the powder better.
You should avoid boiling water when making matcha, as it can create a bitter taste. The ideal temperature should be between 140-175 degrees Fahrenheit for the best flavor.
For those looking to diversify their matcha drinks, Tasting Table has a great DIY recipe for a matcha latte that combines matcha with milk and maple syrup.
Cold brew coffee has a mellower taste compared to hot coffee, and similarly, the temperature of the water used for matcha greatly affects its flavor.
Read at Tasting Table
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