That humidity is the norm for us too in summer, the joys of being below sea level
The same issues with heat and humidity also exist with cold & humidity in that the cold is harder to withstand and cope with when the humidity is 98% than the same temperature and say 80% or 60%. The irony is that it wouldn't feel as cold if it was actually well below zero because the humidity would literally drop out off the sky.
I've camped in -20°C, waking to a layer of ice on the inside of the tent and over the top of the sleeping bag. I've solo camped wild in -15°C, again waking to ice over the sleeping bag and inside of the tent (that particular time needed holes hacking in the river before you could get to running water). We've cycled in similar conditions on more than one occasion including the day that ended our attempt to cycle around the world (it was cold enough that day for blood to freeze on the road, day time temp was around the -14°C with night time temps dropping down to below -30°C) and the irony is, this cold feels colder because it's a wet cold. I know I'd actually be warmer camping on the lawn because the tent is a smaller space to warm up.
Just to add to the fun, there is no heat on the bathroom right now. Showering or bathing is exceptionally challenging. The only reward is running from the bathroom to the sitting room to sit in front of the fire whilst you dry yourself and get dressed. But even the fire is struggling to warm the sitting room at present because the temperature isn't getting warm during the day. It is clear skies at night, so the temperature drops to zero by about 6pm which it holds until mid morning to early afternoon because it clouds over at dawn or just before, so the sun isn't warming the house during the course of the day (solar radiation on a metal tin roof really has a massive impact). So we're getting 18 hrs or so of night time temps with a slight rise in the afternoon (it made it to 5°C today) just in time for the clear skies to ensure all the little heat obtained, vanishes without a trace. It goes dark around 5pm, so we're getting 4-6 hours (today it was 4hrs) of marginally warmer weather before dropping again...
I have to confess the only time I've cycled through the Netherlands, it was the middle of May and yes, the humidity was a factor, as were frosts first thing in the morning. It didn't get really hot until we hit the middle to north of Sweden.