Albert Barnes Commentary Proverbs 25:13

"As the cold of snow in the time of harvest, [So is] a faithful messenger to them that send him; For he refresheth the soul of his masters." — Proverbs 25:13 (ASV)

A picture of the growing luxury of the Solomonic period. The “snow in harvest” is not a shower of snow or hail, which would be terrifying and harmful rather than refreshing (compare 1 Samuel 12:17–18). Instead, it is the snow of Lebanon or Hermon put into wine or other drink to make it more refreshing in the scorching heat of May or June at the king’s summer palace on Lebanon (1 Kings 9:19, note; Song of Solomon 7:4, note).

Even more reviving than the iced wine cup was the faithful messenger. Contrast Proverbs 10:26.