When is it the end of beacon season?

Late last June, a we crunched up hard snow on Easton, it seemed there was not much need. In July I think there definitely was not, and that stayed clearly true as we skied longer or shorter patches in August into October.

Any guidelines on seasonally when it is reasonable and safe to leave the beacon behind?

Good question.
I think it's somewhat of a personal decision.
This is the time of year where I usually bring the avy gear and then if someone on the trip prefers not to "go naked" (avy gear wise, that is  ) then I can capitulate to their preference.
My own personal time to leave the avy gear behind varies with the recent history of the weather and the snowpack. I like to see a long hot spell in the spring causing the typical major spring melt avy events and then some additional time after the spring slides are history for major final settlement of the snowpack where I will be skiing. It could be weeks or even two or three months after the spring slides depending on the weather and the elevation of a planned route, before my gut tells me it is time. If I feel fairly certain that the snowpack for my planned route is isothermal (i.e. settled to a point of a single temperature, non layered, homogeneous mass) then I welcome saving the weight of the avy gear by leaving it behind.
I'd be interested in hearing others' takes on the subject.

O boy, I think this could be a real interesting thread.  I concur with Ron's comments.

Jill and I have spent numerous springs in The Sierra touring and we find the snowpack seems to consolidate earlier there and we usually tour without the avy gear.  For the first couple of years, we would carry avy gear and most locals would ask us why and they would explain why not.

I have noticed that in the PNW our snowpack consolidates in late May/June versus a month or two earlier in The Sierra.

I believe it is a personal issue and I would never encourage or discourage anyone about carrying avy gear in the "late season".

My experience is drastically less than that of Ron and Zap, but my approach has always been to bring it when avalanches are of concern to me or my party.

I've seen pole-deep slop in mid July at 11k on Adams on a hot day in a thoroughly "consolidated" snowpack. Last year, many people, myself included, got surprised to various degrees by the mid-June slide cycle. A number of folks were not. There's recently been an early-mid August storm that deposits fun snow down to 7k or so that probably builds reactive windslab at higher elevations. Given the right conditions and stimulus, snow will choose slide downhill at any time of the year.

Unless weight is a huge concern to me or it's obvious that slides won't happen, I tend to bring my full avy kit. Training weight is good for the times when I do choose to go lighter and faster. If I start to ditch gear it's in the order (probe, beacon, shovel).

Put another way, if you're not sure, consider bringing it.

If I were skiing up high this weekend after the recent rain and storms, avalanches would definitely be of concern to me.

Avy gear won't stop you from getting caught in a slide, of course. .

I'm such a waffle. I always go with the group consensus. I bring it to the parking lot, then decide with everyone else.

I think the answer depends on the current conditions and risk acceptance level.

Last summer two German climbers were buried and killed in Canada. Obviously not the Cascades, but it was a rare summer fatality nonetheless. If I remember correctly, the climbers were buried simultaneously, so who knows if transceivers would have helped.

Snow conditions can be very different above the firn line on glaciers. It is possible to trigger slab avalanches above the firn line at any time of the year, although such releases are rare. Wouldn't it be great to have to worry about new snow avalanches in June, July, and August?

Gosh I could really use a powder fix right now.