From SpaceWeather.com:

MORE STRANGE CLOUDS: Another wave of electric-blue noctilucent clouds (NLCs) swept across northern Europe last night. These mysterious clouds favor high latitudes, but they have been sighted in recent years as far south as Colorado and Utah. Northern summer is the season for NLCs, so be alert after sunset for sinuous, blue-glowing ripples in the western sky.

AND MERCURY: While you’re out looking for NLCs, you might also notice a bright pink “star” beaming through the glow of sunset. That’s Mercury. The planet is moving out of the glare of the Sun and into good position for viewing throughout mid-June.