Zalando is forecasting its profits will be at the lower half of its target range despite order and customer numbers spiking in the second quarter.

The online fashion retailer is expecting adjusted EBIT for the year at the low end of its €220-€270m (£200m-£240m) target range and sales growth in the lower half of its target of 20-25%.

During the second quarter Zalando recorded 29m orders, the highest number in a single quarter. The retailer’s active customers also increased by 15.9% to 24.6m. Customers ordered more than four times per year, in an all-time high.

Zalando grew revenues in the second quarter by 20.9% to €1.33bn (£1.19bn) in the quarter, while it recorded an adjusted EBIT of €94m (£84m) during the period.

It has revealed profits are being held back because of changing shopping habits, which includes a decline in the average basket order size as customers order more frequently.

Zalando also attributes a declining basket size to people increasingly ordering on a mobile device because they order less on smartphones than on a computer.

In its second quarter, the average basket size at Zalando declined 6.4% year on year to €60.40 (£54). The sales mix and gross margins were also impacted by the heatwave across Europe.

Zalando co-chief executive Rubin Ritter said: “The strong development in customer KPIs shows that our engine is running extremely well.

“We’re excited to see that our customer-centric focus is paying off, despite a continued challenging fashion market environment.”

Ritter expects discounting at the end of the summer season will be more pronounced due to the heatwave in Europe.