Homebrewing through the monsoon when humidity is high

What changes in the monsoon

After a hot Indian summer, the monsoon can feel like a gift to brewers. Room temperatures in many cities drop by several degrees, which makes ale fermentation easier to control. Compared with May, when keeping a fermenter at 20 °C takes real effort, July can be close to ideal. Our guide to fermenting through an Indian summer covers the hot months.

The trade-off is humidity. Relative humidity above 80% for weeks at a time affects malt, hops, caps, labels and every surface in the house. Mould spores are everywhere.

Protecting malt

Malt is dried in the maltings to a low moisture content, typically around 4 to 5%. It is hygroscopic, which means it pulls water from the air. In damp weather, an open bag of malt goes slack: it loses its crunch, mills badly, gives lower extract and in the worst case grows mould.

• Buy malt in amounts you will use within a few weeks.
• Store it in airtight food-grade containers, not the paper or woven sacks it came in.
• Add a few sachets of food-safe silica gel to the container.
• Keep containers off the floor and away from outside walls that get damp.
• Smell and bite a grain before each brew. Fresh malt is crisp and sweet. Slack malt is chewy. Musty malt goes in the bin.

Milled malt picks up moisture and stales much faster than whole grain, so mill on brew day if you can.

Protecting hops

Hops are less hungry for water than malt, but damp and warmth speed up the loss of aroma and bitterness. Keep them vacuum-sealed or in airtight bags with the air pressed out, in the freezer. Once a pack is open, reseal it immediately. Our guide to hop storage and freshness explains what happens to hop oils over time.

Mould and sanitation

Higher humidity means more spores in the air and on surfaces. Equipment that would dry in a few hours in summer stays damp for a day. Damp equipment grows things.

• Dry every piece of kit fully before you store it. Hang tubing to drain. Leave fermenter lids off until dry.
• Store equipment in a closed box or cupboard, not on an open shelf.
• Check silicone tubing, gaskets and airlocks for black spots before each brew. Replace anything you cannot clean.
• Clean before you sanitise, every time, as you always should.
• Wipe down your brewing area with a sanitiser solution before you start.

The brewhouse rule we follow: if a surface feels even slightly damp, it is not dry. Wait or wipe.

Caps, labels and bottles

Crown caps rust surprisingly fast in damp air. A rusty cap can taint beer or fail to seal. Keep caps in a sealed jar with a silica sachet. Paper labels peel and spot with mould. Stored bottles should be fully dry before you cover them, or they will grow mould inside.

Power cuts and fermentation

Monsoon storms bring power cuts in many places. If you ferment in a fridge with a temperature controller, a long outage means the fridge slowly warms. A well-insulated fridge holds temperature for a few hours if the door stays shut. For longer outages, a few frozen water bottles placed inside will help.

Keep a stick-on thermometer strip on the fermenter so you can see at a glance what happened while the power was off. A batch that rose by two or three degrees for a few hours late in fermentation will usually be fine. One that spiked during the first two days, when yeast makes most of its flavour, may show extra fruitiness or a solvent edge.

Some brewers in cooler monsoon cities stop using a fridge altogether for ales and ferment in a water bath in a shaded room. Monitor the temperature with a stick-on strip or a probe.

Choosing styles for the season

Cooler temperatures suit clean ales that would struggle in summer. A pale ale or a lightly hopped bitter will come out cleaner in July than in May. Many Indian homebrewers also plan to brew lagers now if they have temperature control, ready to drink when the weather warms again after the rains.

Humidity mostly causes problems you can prevent with storage and drying. Infections, the bigger risk, are covered in our guide to bacteria and infection in brewing. Learning to spot the early signs and trace them back to their source is what keeps a season of brewing from turning into a season of tipping beer down the drain.

Common questions

How do I stop malt going stale in the monsoon?

Store it in airtight containers with food-safe silica gel, buy only what you will use within a few weeks and mill it on brew day.

Is the monsoon a good time to homebrew in India?

Often yes. Lower room temperatures make fermentation easier to control. You just need to manage humidity around ingredients and equipment.

Why are my crown caps rusting?

Damp air. Store caps in a sealed jar with a silica sachet and keep them away from steam and open windows.