I don't really even bother to harden Brassicas. But I don't start them under lights. I start them in the kitchen and once germinated they go into a cold greenhouse for a few days and thence to an outdoor table and finally into the ground. Here it's more a question of getting them used to wind and rain than high or low temperatures.

I'd rather plant my brassicas before a stretch of cloudy/rainy days then before a stretch of sunny days where they will always show wilting during the day and rebound overnight.

I'd probably go ahead and plant now as long as you aren't expecting high winds, heavy rain or hail.

I always put 1/4" hardware cloth rings around my broccoli and hardware cloth over the top weighed down by rocks or bricks to protect them from groundhogs but it also helps protect them from wind and hail.

I always try to plant (anything) just before a stretch of cloudy weather. Those upcoming 4 days should do your plants great and finish off the hardening process, esp since you're already in progress. Since this involves "Brassica plants" they can handle cooler soils better than summer crops like peppers or corn.

I Barely finished my ground work before the sun went down so started planting this morning at dawn, but by 8 am it started raining so I had to finished up in a rain coat.

So thanks for the input which give me to confidence to do it.

I got to say it gets harder every year to get up off my knees, and after planting 250 onions 2 days earlier I could barely move the next morning. I was offered a dozen free mature oak trees a friend cut down, so last weekend I cut them up in 4' pieces and hauled them home. about 8 cords worth. I was a little sore but nothing like planting the onions and involved a different sets of muscles I haven't used in a year.