Haiti’s rainy season is bad enough in a normal year. In April, there’s an average of 160 mm of rainfall, rising to 230 mm in May. At the season’s height, there can be five days of uninterrupted rain. It regularly causes mudslides and flooding, destroying houses, livelihoods and potentially taking lives.

But this isn’t a normal year. The Haitian government initially estimated around 1.3 million people were made homeless by January’s earthquake, although it may be many more than that. Although host families have taken many of those in and some may be able to return to their quake-damaged homes, there are still hundreds of thousands of people crammed into improvised camps and settlements across the affected area.

If those people don’t have adequate shelter, they’re going to lose belongings, be more vulnerable to disease – or worse. In short, it’s a potentially massive problem.

So what are we doing to prevent the rains having such a disastrous effect?

Clearly, we need to provide safer, better living conditions for as many people in the camps as possible in the time available to us. But that’s easier said than done. It’s an incredibly complex issue, which I’ll try and unpick in a series of posts over the next couple of weeks. But there are two main threads to our work right now – emergency shelter materials and sanitation.

The absolute priority is to make sure all displaced people have emergency shelter materials to shield them from the rains – predominantly waterproof tarpaulins. There are more than 50 agencies working on shelter in Haiti, and between us we’ve been getting these materials to an average of 100,000 people a week since the earthquake struck. So we’re closing in on the one million people mark now.

Considering the massive challenges in the early days of the aid effort – destroyed port, blocked roads, clogged airport – this is close to a logistical miracle. It means we’re on track to reach the vast majority of people by 1 May, although because of the uncertainty over numbers of people in need, we can’t be complacent and mustn’t slacken our pace.

We’re also starting to distribute more durable materials, like wood, rope and nails, but realistically we have to accept not everyone will get those before the heavy rains begin. Some work has also started on building more robust transitional shelters, built to last for years, but that’s in the early stages – we’re talking about more than 100,000 structures, which will take months to complete. Frustrating as it is, for the time being, making sure people have simple waterproof materials is still the key to keeping them safe during the rains.

The other area we’re focusing on is sanitation. Toilet facilities in the camps are pretty poor and heavy rain could flood the current camps with untreated sewage water–a potential major health risk.

Red Cross teams, including our own British Red Cross mass sanitation team, are working in several camps to install latrines – more than 1,300 have been built so far – improve drainage, manage waste and raise awareness about hygiene issues among the camp inhabitants. Some interesting techniques are being used to accomplish the latter, including clowns.

For once, the storm clouds gathering above us are real, rather than metaphorical. We have to continue to move as quickly as possible – and continue to work towards stopping a disaster that’s already terrible getting even worse.

As I said above, I’ll write some more over the next few weeks to tackle some of the key questions in more detail.