Our local problem is gulls rather than pigeons, but the solutions seem to be the same. Metal spikes seem to be favourite, they are a bit visually intrusive, but then so are guano and nests.
The adhesive used stands up to rain fine, with spikes lasting for years in situ, but we don't really get extremes of heat or cold by US standards, just cold by UK ones.
I have worked in buildings netted against pigeons, the nets seem to get damaged and ineffective after only a few years, and are pretty ugly IMO. Doing spikes seems to be a more expensive job, but ultimately both more effective and more cost-saving.