Timestamp of ERA-5 zero-degree-level monthly mean

Datasets and Usage C3S - Datasets and Usage
1

I noticed that the timestamp of ERA-5 monthly mean zero-degree-level is 06:00 although the only option in the web interface is 00:00. Is that expected?

Here’s my request:

dataset = "reanalysis-era5-single-levels-monthly-means"
request = {
    "product_type": ["monthly_averaged_reanalysis"],
    "variable": ["zero_degree_level"],
    "year": ["2025"],
    "month": ["02"],
    "time": ["00:00"],
    "data_format": "netcdf",
    "download_format": "unarchived"
}
client = cdsapi.Client()
client.retrieve(dataset, request).download("test.nc")

And the timestamp:

>>> ds = xr.open_dataset("test.nc")
>>> ds["valid_time"]
<xarray.DataArray 'valid_time' (valid_time: 1)> Size: 8B
array(['2025-02-01T06:00:00.000000000'], dtype='datetime64[ns]')