Another idea I had would be something I like to call "City-Wide Events". These are basically large events that can happen certain neighborhoods, districts or even the city itself (Stilwater and Steelport). These include:
Concerts: Increased police presence and heavy civilian traffic especially around the Ultor Dome and Pryor Stadium (newer, larger stadium that replaces the old stadium that was used in the mission Murder-Brawl 31). You'll often hear music emanating from the stadium.
Sports Event: Heavy police presence (a mix of cops, sheriff deputies, ultor security and riot police) and a heavy civilian presence. You'll often hear chanting and yelling when you're near the Arena\Convention Center districts or any of the neighboring areas.
Parade: Heavy civilian presence. Light police presence. Unique parade float variants of the Wellington, Churchill, and Flatbed will spawn. Street venders and mascots have a higher spawn rate.
Snowstorm: Low civilian and gang presence. Medium police presence. Most civilians that spawn will often consists of firefighters and EMT's. Ground will be covered with snow. (Does not affect driving controls).
Heavy Rainstorm: Minimal civilian, law police, and gang presence. NPC's driving vehicles will move much slower or alternatively put the pedal on the metal. Ground is covered by six inches of water. (Does not affect driving controls or on-foot combat)
Protests: Extremely heavy police presence, medium gang presence, and heavy civilian presence. Certain roads may be blocked off by the crowd or police checkpoints. Has a chance to degenerate into a riot.
Riot: Police actively target civilians, civilians will attack police and city property. Stores have a chance of being damaged, (You can still use them as normal) and store-owners will immediately pull out a machete, baseball bat, McManus 2018 or a random shotgun if police try to raid the store, protesters try to loot it or if the Boss tries to rob it. Certain buildings will have smoke and fire emanating out the windows, trash, glass, broken bottles, tear gas canisters and other debris will litter the road, damaged\destroyed vehicles are a common sight and police and protesters will set up barricades. Lastly oppressors and eagle helicopters will do fly-by's over the area.
Gang War: Enemy gang members actively target Saint soldiers, police, and in some cases civilians, swat officers will do routine patrols and gang members will patrol the area in five-man squads or alternatively a column of vehicles supported by several squads. civilians are a rare sight during a gang war.
Lockdown: SWAT, Riot Police, STAG, National Guard and Ultor forces can be seen in five or ten-man squads, law enforcers can be seen harassing civilians (pulling them over, threatening them, asking them a ton of questions) or outright attacking anyone (Police can be seen raiding stores, arresting people, beating civilians,).
(Additional Notes): These can be disabled in the options menu.