An online flyer for the new car, which is understood to be official, confirms the date of the premiere of Ferrari's "149M project".
The current generation of California has the official internal code of F149; the additional M mentioned in the teaser is thought to mean Modificado.
Previously, Ferrari has used the M designation on models that have been upgraded or heavily revised. For example, the Ferrari 360 had the internal denomination of F136. The model that succeeded it, the F430, bore the identifier F136M.
Consequently it's likely the model set to be unveiled is a dramatically revised version of the current California. It's understood that the biggest change for the new California will be the ushering in of turbocharging to mainstream Ferraris.
The latest iteration of Ferrari's convertible model is set to be powered by a 552bhp version of a new Ferrari-designed and built twin-turbo 3.8-litre V8 engine, first used in the Maserati Quattroporte and Ghibli models.
An official name for the new model has yet to be announced, but Ferrari has registered no new trademarks and several sources suggest that it will retain the name 'California'.
Test mules indicate that there is still work to be done on the California replacement, but Autocar understands Ferrari dealers are already taking pre-orders for the model with deliveries scheduled for May, just two months after its debut at the Geneva show.
The styling of the coupé-convertible is understood to have been heavily influenced by the F12, particularly at the front, and the shape of the headlights are said to reflect those found on newer Ferraris, including both the F12 and Ferrari FF.
At the rear of the car, the height has been reduced slightly, although this visual effect is apparently heightened on the production car by some clever lines. The retractable hard-top roof remains.
For the interior, the cabin is also said to have had an overhaul. A new-look dashboard and a completely new multimedia system are among the upgrades.
The 552bhp, direct-injection turbo V8 is adapted from its 523bhp form in the Quattroporte. Our spy photographer reported a louder exhaust note than that of the naturally aspirated V8 found in the current California.
A V6 engine option was understood to be under consideration at one stage, but plans for this have now been dropped.
Ferrari wants to reduce output of the California replacement by around 500 units per year as part of its plans to limit production to improve exclusivity but without harming profits.
Once order books officially open at Geneva, customers are likely to have to wait more than a year for delivery, with initial production preserved for pre-orders.
The price of the California replacement is understood to be approximately the same as the £152,154 of the current model.