Even if a business is only open for 3 or 4 months out of the year, the business will have income and expenses during that timeframe. A business owner can estimate those numbers (budgeting!) and use those numbers to determine how many jobs need performed (lawns mowed, driveways cleared of snow, etc.) in order to at least break even.
Some examples of how breakeven analysis works for service providers and not-for-profits.
Further examples of breakeven analysis for small businesses.
A brief introduction to breakeven analysis for small businesses. How to determine the point at which you’ll sell enough to at least break even.