Hi Paula,
If you want to look back through the weather history of Nelson, take a look on
here . Scrolling down the page will bring you to a small section called History and Almanac where you can insert dates and it will bring up the relevant weather details for them.
This might be a bit more comprehensible as it has charts which show at a glance what the average temps and precipitation are like. It also gives some background info on Nelson.
And, for good measure, here's another one showing archived
weather details for Nelson.