The dramatic flooding occurring in California is an example of the "protection gap" that often occurs with natural catastrophe events (even in developed countries) whereby the amount of economic damage suffered by people and businesses dwarfs the actual insured loss.
Accuweather - video report available here - cites a potential economic damage figure of US$31-34bn.
The latest research from catastrophe modelling firms that we have seen suggests that as take-up of flood insurance is very low in California especially for residential risks with between 1% to 3% of insurable residential properties covered, the actual insured loss to the worldwide insurance industry will be quite low and insignificant notwithstanding that commercial risks' take-up is higher at some 30% of insurable properties.
As the "atmospheric rivers" continue to afflict California we will keep an eye on the situation.
Update 19 Jan 2023 - "Verisk" the US insurance data and analysis firm published a report to subscribers saying that it would not be releasing an industry loss estimate as it did not expect the insured losses to be significant enough.
Update 26 Jan 2023 - Catastrophe modelling firm Moody's RMS has provided an industry loss estimate of US$1.5bn and cited economic losses of US$5bn to US$7bn.