Today, the Jewish festival of love, was a gorgeous day in Jerusalem. The temperature throughout the day was warm but not too hot, the air was clear (as usual), and the morning was cool.
A brisk, clear morning in Hebrew is called בֹּקֶר צַח (BOH-kehr tsahkh), where צח means clear, pure, unblemished. It's not only a description of the morning itself - it's also a wish you might bestow upon someone, much like בוקר טוֹב - good morning (BOH-kehr tohv).
You can use the same word to wish someone a good evening, especially if it's nice outside, with עֶרֶב צַח (EH-rev tsahkh).