Ask HN: Starting a local blog

So I want to start a blog for my city and surrounding areas. There are a couple of problems I am facing. First, I have never blogged a day in my life. And second, what the heck should I blog about?

According to Wikipedia my city (Santa Maria, Ca) has a population of about 102,216. The population was spread out with:

31.4% under the age of 18

12.2% aged 18 to 24

28.6% aged 25 to 44

18.3% aged 45 to 64

9.4% who were 65 years of age or older

The median age is around 28.6 years. For every 100 females there are about 102.2 males.

Agriculture is the main money maker around here. Primary crops include strawberries, wine grapes, celery, lettuce, peas, squash, cauliflower, spinach, broccoli and beans.

I have no idea what readers might be looking. So, my questions are:

* Is it a good idea for me to blog about random topics and tie to them to my community until I find a niche?

* Or should I focus on finding my niche before I write a single word?

Thank you in advance for any advice.