Temp to reseat pavers

If they were done properly the "glue" is a concrete product - probably an acrylic modified thinset mortar . It just needs to be above freezing for concrete to set . Dig the old stuff out enough that you have a "bed" of mortar a half inch or more thick to reset the paver(s) into so you can level it with the rest .

The manufacturer of the adhesive should list the recommended temp. range right on the package. If not , check their on-line spec sheet.

Just for an example, Loctite epoxy recommends to use between 39 and 95 F

If you have to ask, it is probably too cold to go out and do a good job. Read what the glue label says. Most are at least 40 or 50 degrees.

I've used polyurethane adhesive with excellent results.

Actually the question was more along the lines of, I want to know when I have to actually go and get the stuff (grin)

Tell his wife it should not be touched until it is a steady 65+ in mid June.

My guess is they used regular thin set or type S and they should have used "flex" with the acrylic binder.

I would check what was used before. I have set a lot of brick pavers on concrete. The adhesive I have always used was plastic roof cement, as close to the old cutback adhesive as possible. I've never had any come loose. Once set, brush in/on fine samd to fill any voids.