In the recent IARU contest 15 Meter conditions showed a radical improvement over last year, though the solar flux was only around 110. The daypath to Europe in the morning brought a lot of activity to the band, and some really good running rates. The opening lasted well into the afternoon (after sunset in Europe), because seasonally we still have the high nighttime MUF's. Signals propagate nicely over regions where it is evening, then extend to regions of daylight. Another such path is the morning path to southeast Asia. Conditions are even good over the pole into central Asia during windows in the morning and evening. All these paths will continue to improve in coming years, and additional openings will occur on 15 that require the higher solar flux.
But it is summer, and a sun-baked ionosphere does lower the daytime MUF. Expect conditions to deteriorate rapidly on 15 over the coming month. We loose 10 Meters for high latitude DX work beginning in May through August even at the top of the cycle for the same reason. Most activity will move to lower bands, such as 17 & 20. Midsummer conditions aren't good for the low bands either, because of the high static levels. Thus, DX activity in mid-summer tends to concentrate on 20 Meters due to a lack of other options.
20 is primarily a night path band now, with excellent openings during the day into areas where it is night. Europe starts to open in the early afternoon, with signals building to a peak before sunset amid the high daytime noise level. In the late evening we get the other end of this path, which propagates into the Asian afternoon. On the dark end of this path, the band is quiet and weak signals are easily copyable.
Morning brings a daily pipeline to Asia on 20, extending to southeast Asia, Indonesia and beyond. Long path to the northwest is at a seasonal peak during the summer, but from Texas only a few rare island countries exist at the far end of this daily opening: FT/WXZ, VK0/H, 3Y/B, ZS8 & ZD9. Westerly long path to the southern portion of Africa also peaks in the summer, while the Antarctic paths to Europe and southern Asia are out of season. Short path to Africa is open for much of the afternoon and evening.
Good conditions will be found on 15 for a while longer. As midsummer conditions overtake this band, look for good day and night path conditions on 17 to prevail through most of the summer.