When writing your story, the big holidays like Christmas or Mardi Gras sometimes slip in, but there are a whole lot more little things, if taken into consideration, could enhance the plot—either adding color, tension, relief, opportunity for action, or become a hindrance. Theses little things are often overlooked which could add realism to your story. For instance, banks are closed on certain days as are government entities. Extra time to break in. Not all states in the US observe the same holidays, or they use a different name. For instance, in Arizona there is Civil Rights Day (in lieu of Martin Luther King Day). South Dakota honors their Native Americans on that day. In Nebraska, there is Arbor Day to celebrate planting trees. In Louisiana, there is Marti Gras Day (Yeah!) and Good Friday. The “Start Planning” website at http://publicholidays.us/ lists events in each State.
“Holidays and Observances Around the World” at https://www.timeanddate.com/holidays/ provides information about what is going on in the location you are writing about. Fantasy writers should give some thought to creating their world’s calendar.
Another thing to consider is “Daylight Savings Time.” There are countries outside of the US that who that [useless and aggravating] system. As an example, a character must be in Kingman, Arizona to deliver a ransom no later than 6 p.m. It is a 1-hour, 30-minute drive. He can not get away until 4:30. That would cut arriving awfully close. He speeds to reduce the time. A Trooper pulls him over north of Kingman (they like to hang out there) and issues a ticket. It takes 20-minutes. Disaster? No. Arizona doesn’t observe Daylight Savings Time so he has plenty of time to make the drop. By utilizing that one, tiny detail, the writer has created lots of tension. The link above mentions if DST is used in the country of your choice.
Some other things that could add interest to your story is sunrise and sunset, and moonrise, moonset, and phase at http://sunrisesunsetmap.com/ . That might seem a little OCD, but this information was used in an American West story set in the late 1860’s. Knowing when the main character could start and end daylight travel, and if it were possible to have enough moonlight to travel at night suggested some interesting changes and details, especially considering the following: The character’s travels are also challenged by the weather.
At https://www.wunderground.com/history/ the Weather Underground provides historical data for the United States. For other parts of the world there is Travel Weather at http://www.weatherbase.com/ . There are a number of other sites that might be more useful, some going further back in time than 1945, but generally just pick a particular time of the year and go for it. Yes, you could manufacture your own data, but challenge yourself by sticking to events within your chosen time frame.
In the Western story, using these things together, the main character travels across the Southwest during July and August. Temperatures are up to 110-degrees, a hot, dry, 25-mph wind makes daylight travel harsh to dangerous as there is little water along the route. Using pre-dawn and late evening light added to daylight when the temperature is still reasonable before having to stop and take shelter, would he be able to make it to the next water hole? Was there enough moonlight to travel at night? What about thunderstorms and resultant stream flooding, maybe a tornado which have a tendency to pop up in the afternoons? In another story, what if your Kung Fu hero has to fight his way out of fifty assassins to save the day? In a driving rain? On mud and through puddles of water? Under a full moon that can’t decide to hide behind a cloud or not?
I especially like using weather factored into a story. Consider what we are usually handed—chase scenes, for instance. The good guys are pursuing the bad guy down a crowded sidewalk, knocking people every which way, crossing streets without getting run over and no crashes—in ideal weather. Now, what would happen if the chase took place during a noon lunch break, in late February? It’s snowing a bit, but the sidewalks are an ice rink. Lots more interesting action and tension. What happens to the baby in a carriage when the mother is knocked down? What about the two causing all the trouble as they slip, slide, and become human bowling balls? What happens when the bad guydarts across the street causing a metro buss to go sideways?
Attention to little details such as these put in combination can bring to mind endless excitement, tension, even comedic challenges. Perhaps that difference will spark more interest in your readers.