This year, Steam's Summer Sale will apparently begin June 23, according to a user on Reddit. MrFreemanBBQ shared a Russian-language screenshot purportedly from Valve, suggesting that this year's sale period will run from 9:45 a.m. PT on June 23 until July 4 at 10 a.m. PT.
Valve has not announced that a Summer Sale will be happening this year, but it would be in keeping with tradition. That the dates are leaked in advance — by a Russian tipster, no less — is also becoming a pattern. Last year, MrFreemanBBQ was responsible for giving Steam customers the heads up about when the Summer Sale 2015 was set to begin. After posting them on Reddit, the dates appeared on Russian social network VK, picking up further traction.
Shortly thereafter, Valve announced the Summer Sale dates, which matched what MrFreemanBBQ suggested ahead of time. The Redditor has done this with several seasonal discounts on Steam in the past, including the Summer Sale in 2012 and the Holiday Sale in 2013.
PayPal was responsible for an early date announcement for 2015's Winter Sale. A promotional image shared by the website mentioned the start for the Winter Sale ahead of Valve's confirmation.
Despite his bonafides remaining unknown, MrFreemanBBQ has been correct about each of his leaked sales period dates. Still, we've reached out to Valve for confirmation.