Earth is about to be hit by a double-stream of solar wind. The two streams are flowing from holes in the sun's atmosphere. Solar wind flowing from the first coronal hole is expected to arrive on Aug. 27-28. A more potent stream of solar wind flowing from the second coronal hole should reach us on Sept. 1-2. G1-class geomagnetic storms are possible on both dates, although Sept. 1-2 is more likely to experience storm conditions.