For years I have waited until late October to bring the jade plants back into the house for winter. Overnight lows are likely down to 5 or 6 degrees C by then. They always lose a lot of leaves when the come in, but quickly replace them with new leaves. It occours to me that this leaf loss may be due to the temperature shock of changing from lows and highs of 5 to 10 C outdoors to a steady 20 C indoors. Environment Canada's average temperatures for today (September 5) are highs of 20 C and lows of 12 C. Perhaps they should come inside now, although they would miss a month and a half of better light. When should jade plants come indoors?
A number of documents like this one suggest the plant should be moved indoors before the first frost: Jade Plant, Crassula ovata – Master Gardener Program. The Missouri Botanical Garden recommends doing so sometime in mid-September but they're in a colder climate zone than us on the west coast: Gardening Help FAQs. The author of the following document claims the plant will go dormant around 10C: How to Keep Jade Plants (.pdf). Perhaps that is what was happening to your plant. A citrus tree will similarly drop its leaves if it is exposed to light while its roots are dormant. If you don't want to bring the plant in early, you might try keeping it in darkness once inside until it and the soil warms to room temperature before exposing it to light.
Friends here in the UK have brought theirs inside already. September 1st is always on the callander reminder to do this. Temperature here at night has drifted to below 6°C over the last week. Jade plants do not like it that cold !!! Tbh anything below 10 °C is risky.
