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How to Adjust Espresso in Humid Weather? How to Make Espresso Parameters Taste Good?

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, Guangzhou has entered the damp 'return to the south' season, with walls covered in water droplets, floors that never dry, and clothes that become damper the longer they hang. And of course, there are the coffee beans that are most afraid of moisture. How does the 'return to the south' season affect espresso production? Baristas who work at the counter should have deep experience with this. In daily weather with small temperature differences and dry conditions, extracting espresso

Guangzhou has entered the damp "Huinantian" season, with dewy walls, perpetually wet floors, and clothes that become damper the longer they hang. Of course, there are also the moisture-sensitive coffee beans.

How Does the Huinantian Season Affect Espresso Extraction?

Baristas who work at the coffee counter should be well aware of this. In typical weather with minimal daily temperature changes and dry conditions, extracting espresso is relatively stable. The parameters adjusted in the morning generally remain consistent throughout the day.

However, during rainy days or the Huinantian season, extraction deviations become more significant. This is because when environmental humidity is high, coffee beans in the hopper are easily affected by moisture. During grinding, they are also susceptible to water vapor interference, causing coffee grounds to clump and lose flavor. When extracting espresso, this leads to very unstable extraction phenomena.

Another factor that slightly affects extraction is that when humidity increases, atmospheric pressure decreases. Espresso machines will have slightly lower pressure during pressurized extraction than usual. Consequently, the extracted coffee flavor will be weaker than expected.

Therefore, it's essential to find a stable adjustment method to ensure consistent product quality.

How to Cope with Adverse Weather Like the Huinantian Season?

First, minimize moisture exposure to coffee beans as much as possible. Keeping windows and doors tightly closed can significantly reduce the intrusion of outdoor moisture. If conditions allow, use a dehumidifier to maintain indoor humidity.

Since nighttime humidity is greater than during the day, after closing business for the day, coffee beans in the grinder's hopper should be returned to sealed bags (containers) for storage. The hopper needs to be wiped clean because moisture mixed with residual coffee oils can easily produce unpleasant odors. Residual grounds in the grinding burrs and powder dispensing chute should also be cleaned as thoroughly as possible.

Second, address the problem of coffee ground clumping. On normal days, freshly ground coffee rarely experiences clumping issues (assuming the grinder itself is functioning properly), and using a distribution tool to distribute grounds before extraction yields stable results.

However, when severe clumping occurs, distribution tools cannot achieve the effect of "evenly distributing coffee grounds." The clumped areas remain denser than other parts, naturally leading to unstable extraction.

Therefore, the simplest solution to this situation is to distribute the grounds by hand, breaking up clumped coffee grounds. For those with the budget, a needle distributor can also achieve evenly distributed results.

How to Adjust Stable Extraction Parameters

Due to reduced pressure and high humidity, when extracting at the usual grind setting, water penetration will be slower, and extraction time will be longer than usual. FrontStreet Coffee suggests the most stable approach is to increase the dose and use a coarser grind setting.

A coarser grind can reduce the degree of coffee clumping and is also a way to control time, while increasing the dose ensures more stable extraction.

Below, FrontStreet Coffee provides an example for everyone's understanding. Typically, FrontStreet Coffee's extraction parameters are 19.5g to extract 35g of coffee liquid, with a time of 30 seconds (including 6 seconds of pre-infusion). When encountering high humidity, you can first increase the dose to 20g, still aiming for 35g of coffee liquid, and adjust the grind setting to control extraction time within 30 seconds. Then, make fine adjustments based on specific flavor feedback.

Especially during weather conditions like the Huinantian season that change significantly, adjusting once in the morning won't maintain stability throughout the entire day. Adjustments should be made in real-time based on actual extraction conditions. Here's a reference for everyone: when extraction time differs by more than 3 seconds, it's time to adjust the grind.