“Less” is used with uncountable nouns. “People” is a countable noun, so you should use “fewer”.
After the verb “plan”, use the infinitive “to travel” rather than the gerund.
3. Redundant word:
The preposition “over” should be omitted because “this year” means “over the course of the year”.
4. Adjective form:
The word “worse” is the comparative adjective for “bad”. Since nothing is being compared, you should just use “bad”.
5. Verb tense:
The time frame is from a point in the past until now, so you should use the present perfect tense (“has happened”) than the simple past.
6. Redundant word:
The preposition “to” isn't needed here.
Fewer people in Canada are planning to travel this year because of the bad weather that has happened in many parts of the country recently, and also because it is expensive.