I want to say that it's not slippery outside (shoe/ground), but when the rain/water gets into your shoes, it's slippery inside your shoes (feet/shoe), so if you wear a loose fit, then please becareful when walking in the rain. I nearly sprained my ankle once because of this.
That said I will wear them on rainy days, but I will watch out when they start to wear down and gets thinned. Thank you all 樓上媽媽 for the tips!!