Weather and your order.

What rain actually does.

Drying stops. Agricultural products dried in the sun cannot be dried in the rain, so producers either wait or dry badly. Badly dried material is where mould toxins come from.

Roads fail. Rural collection roads become impassable, which delays material reaching a mill rather than delaying the mill.

Loading gets wet. Containers stuffed in the open during rain take on moisture, and the goods discover it three weeks later.

Harvest timing shifts. Crops follow rain rather than a calendar, so a season quoted last year is a guide rather than a date.

That it differs by island.

Java and Sumatra are broadly wetter in the northern winter months and drier in the middle of the year, with local variation.

The eastern islands are drier overall, with a more pronounced dry season, which is why salt and some crops concentrate there.

Sumatra's west coast is wet for much of the year, which is exactly why drying practice matters so much for the crops grown there.

The practical consequence is that a supplier's seasonal advice applies to their region and not to the country.

How to plan around it.

Ask when the material was dried rather than only when it was harvested. That is the question the certificate does not answer.

Buy the drying condition into the specification: moisture, and where it matters a mould toxin result on the shipped lot.

Expect longer lead times in the wet months on anything sun dried, and build the buffer rather than pressing.

For loading, ask whether the container is stuffed under cover. On a wet day in an open yard this is a real quality question.

Weather at sea.

Typhoon and storm seasons on the routing affect schedules more than conditions in Indonesia do.

Container rain is a moisture problem created at loading and revealed at sea, so it belongs in the same conversation as drying.

Reefer and chilled cargo suffer most from delay, so weather-related schedule risk is a bigger commercial factor on those products.

Questions buyers ask.

Read next.

• When Indonesia stops working

  Idul Fitri, Nyepi and Chinese New Year decide whether an order ships on time. How the holiday decree works and why next year's dates are not real yet.

• Moisture and water activity

  Moisture content is what you paid freight on. Water activity decides whether it spoils.

• Packing for a tropical voyage

  Container sweat, mould, insects and crushing. Four failure modes that arrive as claims, and what stops each.

• Container loading and what actually fits

  The cubic capacity figures in circulation disagree with each other. What really decides a load is weight, geometry and the carrier's own specification.