Only one remark: the additional variables include a few numeric fields (iso_time, wmo_wind, wmo_pres, dist2land, storm_speed, storm_dir). None of these are interpolated when interpolate_missing = True. Do we want to extend the code to interpolate missing values here or leave that to the user?

These variables are not reported variables, but are provided by IBTrACS as a courtesy to users, e.g. dist2land, storm_speed, storm_dir. They never have missing values as far as I understand it. For wmo_wind and wmo_pres, I think that nobody should use these. If somebody is interested in those values, they should use the provider="official" feature.

The documentation of interpolate_missing includes a complete list of variables that are affected by this setting, and I think that's clear enough.