This one always brings out a lot of Russian Navy comm, and increased activity in general. Exercises are in progress in the Baltic Sea, the Black Sea, and off the Kamchatka Peninsula. These are live-fire exercises involving large numbers of warships, and usually with a staged coastal troop landing somewhere.
The Baltic exercise will continue for the rest of August. The Black Sea exercise lasts until August 20. The duration of the Kamchatka exercise is not known. The first two should be easily audible in Europe and the US East Coast, while the third should boom into the US West Coast at night.
The naval "cluster beacons" usually light up for this one. Look for the single-letter CW identifiers at .1 kHz spacing, about half a kHz up and down from these frequencies:
3595, 4558, 5154, 7039, 8495, 10872, 13528, 16332 and 20048 kHz.
Recent reports also indicate VLF activity on 18.1 kHz, and CW traffic on 3835, 4076, and 4441 kHz.