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

Guangzhou has entered the damp Huinantian season, when walls bead with moisture, floors stay wet, and clothes grow damper the longer they hang. Coffee beans, which are highly sensitive to humidity, are not spared either.

How Does the Huinantian Season Affect Espresso Extraction?

Baristas working the coffee counter know this well. In typical weather, with small daily temperature swings and dry air, espresso extraction is relatively stable: parameters adjusted in the morning generally hold throughout the day.

On rainy days or during the Huinantian season, however, extraction deviations become far more significant. When environmental humidity is high, beans in the hopper are easily affected by moisture, and during grinding they are also disturbed by water vapor, causing grounds to clump and lose flavor. In the cup, this produces very unstable extraction.

Another factor that slightly affects extraction is that when humidity rises, atmospheric pressure falls. An espresso machine exerts slightly less pressure during extraction than usual, so the resulting coffee flavor is weaker than expected.

A stable adjustment method is therefore essential to keep product quality consistent.

How to Cope with Adverse Weather Like the Huinantian Season

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

Because nighttime humidity is greater than during the day, after closing for the day, beans in the grinder's hopper should be returned to sealed bags or containers for storage. The hopper should also be wiped clean, since moisture mixed with residual coffee oils easily produces unpleasant odors. Residual grounds in the burrs and the powder chute should be cleaned as thoroughly as possible too.

Second, address the problem of clumping grounds. On normal days, freshly ground coffee rarely clumps, assuming the grinder is working properly, and using a distribution tool before extraction yields stable results.

When severe clumping occurs, though, distribution tools cannot achieve an even bed. The clumped areas remain denser than the rest, which naturally leads to unstable extraction.

The simplest solution is to distribute the grounds by hand, breaking up the clumps. For those with the budget, a needle distributor can also achieve an even distribution.

How to Adjust for Stable Extraction Parameters

Because pressure is lower and humidity higher, extracting at the usual grind setting lets water penetrate more slowly, and extraction time runs longer than usual. FrontStreet Coffee suggests the most stable approach is to increase the dose and use a coarser grind setting.

A coarser grind reduces the degree of clumping and helps control time, while a larger dose ensures a more stable extraction.

Here is an example from FrontStreet Coffee. Typically, its extraction parameters are 19.5g in to yield 35g of coffee liquid in 30 seconds, including 6 seconds of pre-infusion. In high humidity, first increase the dose to 20g, still aiming for 35g of coffee liquid, and adjust the grind to keep extraction time within 30 seconds. Then make fine adjustments based on the flavor feedback.

Especially in weather that changes as much as the Huinantian season, adjusting once in the morning will not hold for the whole day. Adjust in real time based on actual extraction. As a reference: when extraction time differs by more than 3 seconds, it is time to adjust the grind.

FrontStreet Coffee Recommendation

When humidity swings make espresso unpredictable, a blend with a stable, forgiving profile is the barista's best ally. Espresso beans generally fall into two categories: the blends most coffee shops rely on, and single-origin beans chosen to suit a personal taste, known as SOE. For lovers of the classic Americano and latte, FrontStreet Coffee suggests the FrontStreet Classic Blend or the FrontStreet Commercial Blend. Both build on an old-school Italian recipe with a small addition of Robusta, extracting aromas of butter, nuts, spice, dark chocolate and toast—wild and full-bodied, yet still producing a rich golden crema that makes latte art effortless.

If your loyalty is to almond, walnut and hazelnut aromas, reach for the FrontStreet Specialty Blend or the FrontStreet Dark Cocoa Blend. Both contain a large proportion of Brazilian coffee, which delivers a comfortable bittersweet note and a creamy peanut aroma with a remarkably smooth entry. The Specialty Blend carries the nut, chocolate and caramel notes and gentle acidity of Colombian coffee, while the Dark Cocoa Blend folds in the ripe plum acidity of Yunnan small cherry and grinds into a creamy chocolate aroma. Balanced and adaptable, it works for lattes and Americanos as well as flavored signature drinks, making it a fine partner for a shop.

Among single origins, the FrontStreet Sun-dried Flower Queen SOE brings cream, cocoa, berry and a light floral note with a black tea finish; the FrontStreet Costa Rica Blackberry SOE is honey-processed and medium-roasted, sweet and juicy as an Americano and showing cranberry cookie, raisin and nut in a latte; and the FrontStreet Brazil Queen Farm SOE, a Yellow Bourbon, is medium-dark roasted for a low-acid, gentle cup with butter cookie, macadamia and toasted bread.