May. They become neither friendly nor familiar to the unsuspecting backcountry user. The notoriously high precipitation swells rivers and creeks to many times their normal size until even the smallest creek crossing can become difficult or dangerous to cross.
Footbridges often wash out.
Standing water can be knee deep for long stretches. The safest time to cross mountain streams is from sunrise to noon. After noon, melting snow water will increase flows until nightfall. In the High Country Naturally snow prevails, therefore, avalanche hazard is a concern. Map skills, general route finding and common sense are essential.