Yet more evidence has been uncovered to support the theory that Apple will launch new iMacs at its 20 April spring event tonight.

MacRumors has noticed a shortage of 21.5in iMacs at US Apple stores, which is frequently a sign of an imminent launch. Knowing that new models are about to appear, Apple will start to wind up production of the current version so it isn't left with a mountain of unwanted hardware.

On the UK store, too, the non-4K version of the 21.5in iMac is showing a delivery date of between 29 April and 7 May, a slip of one to two weeks compared to the expected 23 April, which is reported for the other models.

New iMac availability

Apple's spring event tonight was initially expected to focus on a new iPad Pro and potentially the AirTag object tracker. But more recently sources have started to suggest the company might be plotting a surprise update to its all-in-one computer. In March, for instance, a number of iMac configurations disappeared from Apple's site.

The big iMac news is expected to be that the Intel processors will be replaced with the powerful M1 chip (or an upgraded M1X). But it is also rumoured that the computers will be given new sizes and released in different colours, potentially evoking the vibrant G3 iMac models from the 1990s.

Last autumn, the Mac mini, MacBook Pro and MacBook Air were all updated to include the M1 chip, which leaves just the iMac and Mac Pro to be upgraded before the processor switch-over is complete.

The event starts at 6pm UK time. Here's how to watch the spring event.

You can catch all the latest leaks and rumours in our new iMac hub. If you're more interested in the models that are currently available, find the lowest prices with our guide to the best iMac deals.

This article originally appeared on Macworld Sweden. Translation by David Price.