For all the effort and money expended on forecasting, we’re pretty rubbish at it. This weekend, much of the south of England has warnings for severe thunderstorms and local flooding. Even the meteorologists accept that they can only forecast that they could affect a broad area. Yesterday, we enjoyed a fine sunny day instead. Forecasting numbers of those suffering Covid-19 and becoming seriously ill from it has been similarly little better than expensive guesswork. When one model doesn’t give the answers you expect, you can always use a different model which might.

With macOS, even nowcasting whether a new update is a full release, or just a final candidate, proved impossible last week. On Monday, when Apple had been expected to release 11.5, it instead provided developers with a second release candidate – what it used to refer to as a Golden Master (GM). The following day, an update purporting to be 11.5, without any qualification as a release candidate, showed up one of my M1 Macs. It turned out that this hadn’t been generally released, and may just have been the same release candidate. The following day, exactly the same update apparently went on general release, although some users saw it briefly before it vanished again.

Having established my credentials as a forecaster as accurate as a modern meteorologist equipped with a supercomputer, I now look ahead to what’s likely to happen with Macs over the coming few months.

I suspect that Big Sur 11.5 is the last ‘minor’ update of its cycle, and that we’re unlikely to see 11.6. Big Sur was released late in comparison with other recent major versions of macOS, in November, when we might have expected to be using its first minor update. The update to 11.5 matches the timing of x.6 in other release cycles. Furthermore, although in previous minor updates to Big Sur, Apple has released the first beta of the next update around the same time as the release of the previous update, this time there are no reports that 11.6 beta has been made available to developers. I don’t think it will be.

From general reactions to the current public beta-release of Monterey, it’s already pretty feature-complete and maturing well. That would put it on target for a September full release, which is when Apple also needs to at least announce the next round of Apple Silicon Macs.

With four different M1 models filling the lower end of the Mac range, if it’s going to complete the transition of most of its hardware to Apple Silicon this year, Apple needs to start shipping successors to the M1 early in the autumn/fall. The 24-inch M1 iMac was announced three months ago, and has now been shipping for two months. If mid-range and higher-end models based on ARM processors don’t appear soon, Apple’s transition may falter.

Components will inevitably be a major determinant of Apple’s timing. TSMC, supplier of the SoCs in Apple Silicon models, has recently been making more favourable noises about the current chip shortage easing, which bodes well. Rumours that TSMC has been manufacturing the successor to the M1 have been circulating since late April, although there has inevitably been no confirmation. Other key components such as displays still seem to be in short supply, but that could of course be an effect of production of new Macs, rather than the cause of delays to them.

Apple needs to release higher-end MacBook Pros and iMacs with full-size displays before the end of October, which would coincide well with Monterey being released in September, together with announcements of those new Apple Silicon Macs. And that makes it very unlikely that Big Sur 11.6 will ever exist.

The final question is when Apple intends providing its replacement for the iMac Pro, which it discontinued last March, and the Mac Pro itself. That depends when their SoCs are ready, which now looks more likely to be early next year. That would give the Mac Pro a life of just over two years, a stark contrast over its immediate predecessor which lingered for six in all. It’s possible that Apple will announce the replacement in December, to coincide with previous models.

Sticking my neck out and being more specific, this is what I expect to happen:

• by mid-September, an Apple Event releasing Monterey and announcing new Apple Silicon Macs, including higher-end MacBook Pro and iMac models;
• between then and the end of October, shipping of those new models and discontinuation of all Intel models apart from the Mac Pro;
• in December or January 2022, announcement of the Apple Silicon replacement for the Mac Pro, shipping early in 2022.

Where would that leave those who purchased Intel models? In the Intel transition, Apple maintained PowerPC support in its current release of macOS from early 2006 to the end of August 2009, well over three years. I’d be shocked if Apple were to stop building Universal versions of the current release of macOS before September 2023, and hope that they’ll exceed that by a year.

I can hear the thunder rolling in the distance already.