Have a search for "SP13 waterproof connector". From what I can see, they come in pin configurations from 1-pin (!) to 9-pin (no 8-pin?) all in the same size body.
That picture looks like Armoured Cable, or SWA (Steel Wired Armour). It's usually for outdoor power cables that tend to have a lot bigger cross section like 6mm^2 or 10mm^2.
What do you want to use it for? Voltages?
Will it be buried or on the surface?
I suppose any old 3-core cable would do for a hobby scenario. Some of the smaller diameter 3-core mains cable may be suitable. I'm in the UK, so something like this from ScrewFix may be ok:
Says it's suitable for Pond Pumps & Other Outdoor Cabling. If you are powering the DHT22 at 5V, then you are limited to around 30m (according to a quick web search).
Hopefully others will offer their advice on suitable cable if ordinary cheap cable is a poor choice.
Bulgin make some very nice, robust, (but expensive) IP68 connectors in their Buccaneer series. The parts from the range can be mixed and mached for greater flexibility, such plug/socket, inline/panel mounted, number of ways and cable gland sizes, etc... The standard series uses screw terminals for cable termination.
I often see standard and mini 4000 series Buccaneer connectors used on outdoor meteorological equipment.
Regarding cables, it's probably worth checking their UV resistance, although standard black/grey PVC is usually pretty good in this regard.
If you put a drip loop in your cables and bring them up underneath the hive or other box where drips, runs, and wind-driven rain can't reach, a waterproof connector is not necessary. I have a bird house with plain Ethernet connector underneath that's been working fine for 10 years or so.
