Seasonality affects every part of the supply chain. For e-commerce brands, demand doesn’t stay consistent throughout the year, and neither do the operational pressures behind getting orders out the door. Weather, bank holidays, school holidays, staffing levels, promotional events and customer behaviour all have a direct impact on fulfilment performance.
Summer is a good example of this. While many brands naturally focus on Black Friday and Christmas peaks, warmer months bring their own challenges that many e-commerce businesses need to prepare for well in advance.
One of the biggest seasonal factors is changing customer demand. Different products move faster depending on the time of year, and that affects everything from stockholding to warehouse space and courier capacity. Research commissioned by Royal Mail found that 66% of UK SME retailers expected summer sales to increase, with warmer weather and bank holidays among the biggest drivers behind that uplift. The same study found retailers expected an average sales increase of 28% during the summer months.
Fulfilment In The Summer
For fulfilment operations, that increase in demand can create pressure quickly if inventory forecasting is inaccurate. Seasonal products often require businesses to commit to stock earlier, particularly if products are imported or rely on longer supplier lead times. If brands under-order, they risk stockouts during peak trading periods. If they over-order, they risk carrying excess inventory into quieter months.
Weather is another major factor. Extreme heat, storms and flooding can all affect transport networks and delivery performance. Summer heatwaves can create operational issues for warehouses and delivery fleets, particularly when handling temperature-sensitive products such as cosmetics, supplements, food or beverages. Logistics providers also have to manage the increased risk of delays caused by network strain and infrastructure disruption during periods of extreme weather.
“When it comes to forecasting, we take a really practical, real-world view,” says Claire Lisle, Head of Information Technology at TSP Fulfilment. “We’re not just looking at historical sales—we’re factoring in everything that drives demand in e-commerce, from peak periods and promotions to weather, Prime events, and key seasonal moments like Mother’s Day that can significantly influence order volumes.”
And while bank holidays over the summer bring much respite to customers, for e-commerce brands they create additional complexity. They reduce the number of working days available for dispatch and delivery, order volumes often increase immediately before and after them. This creates compressed fulfilment windows where warehouses, couriers and customer service teams all experience heavier workloads in a shorter period of time. May bank holidays are traditionally one of the most disruptive periods of the year because of shortened working weeks and reduced transport availability.
Managing Expectations, Managing Staff
For businesses managing this, it means planning further ahead than usual. Cut-off dates need to be communicated clearly to customers, inventory needs to be positioned correctly, and fulfilment teams need enough labour capacity to absorb short-term spikes in order volume.
Summer holidays also impact staffing. Annual leave increases during July and August across warehouses, carriers and supplier networks. At the same time, many e-commerce businesses continue running promotional campaigns and seasonal launches. That combination can place strain on operations if labour planning is reactive instead of proactive.
Some logistics providers report workforce reductions of 15–20% during summer months because of holiday absences. For companies relying on lean fulfilment operations, that can lead to slower dispatch times, delayed inbound processing and increased pressure on customer support teams.
Consumer behaviour changes seasonally too. During summer, customers are often away from home more frequently, which can increase failed delivery attempts and place greater importance on delivery flexibility, tracking visibility and alternative safe-place options. Weekend deliveries and nominated delivery windows become more important during these periods.
Takeaways
Businesses that manage seasonal disruption best are usually the ones that prepare earliest. Accurate forecasting, flexible warehousing, strong courier relationships and clear customer communication all make a significant difference when demand patterns change.
“We work closely with our clients from onboarding following onto long term partnerships,” Claire concludes. “We want to understand what’s coming down the line, and by combining their insight with our data and experience, we can plan ahead properly—making sure the operation is ready to scale when it needs to, without compromising on service.”
For e-commerce brands, fulfilment should never be treated as a fixed operation. Seasonal changes affect stock levels, delivery expectations, staffing, courier performance and customer behaviour throughout the year. Understanding those pressures—and planning for them properly—is what keeps operations moving smoothly when demand inevitably shifts.
