Interestingly, if this March is colder than average, it will be third time in the last decade that an exceptionally warm March (CET at 8°C or above) was followed by a cold one.
2012: 8.3 (8.3 legacy) - 2013: 2.8 (2.7 legacy)
2017: 8.8 (8.7 legacy) - 2018: 5.0 (4.9 legacy)
2022: 8.0 - 2023: ?
Only a very short sample of course. If you go back further this isn't the case, just an interesting pattern of the last few years.