I don't know if I've lived here long enough to say with certainty that it's unseasonably warm, but... 20 degrees in mid-May!? Alder tree is still green (front left), birch is midway through dropping its leaves (back right).
It's been averaging 15 C for a month now. No frost. Is that... normal?
Stuff is still growing. Even the salad greens! Watercress (photo below, front left on the foreground) is sprawling like a king. We eat watercress almost every day, but it seems to be keeping up with our eating speed, so we're not running out of it. Tomatoes (they are in the planterboxes, ie they are not inside a greenhouse) are still ripening.
And, if anyone's interested: we've had planterboxes for about a year now and I've discovered that slugs don't seem to want to climb up in there. Where we had kale growing behind the house in the ground, slugs were eating it, but the kale in the planterboxes - not so much. I guess slugs don't like crawling over rough-sawn timber to get to the plants. Either way, yay for me!
Loving, loving, loving the boxes! The only disadvantage I can think of is that they're expensive to set up initially (especially if you do it like us, with 200 mm x 100 mm macrocarpa timber), but once they're up and running, they're awesome.