Brown Blonde Highlights typically last between 6 to 8 weeks before they start to fade or show noticeable root regrowth.However, the exact duration can vary based on several factors:

1. Highlight Technique:
   - Balayage: This hand-painted technique creates a more natural, blended effect and can last up to 3-6 months before needing a touch-up.
   - Foil Highlights: These are more precise and can last around 6-8 weeks.
   - Babylights: These fine, natural-looking highlights can last up to 10-12 weeks.

2. Hair Growth Rate: Faster hair growth will make the roots more noticeable sooner, requiring more frequent touch-ups.

3. Maintenance Routine: Using color-safe shampoos and conditioners, applying toners to combat brassiness, and protecting your hair from heat and sun exposure can help extend the life of your highlights.

4. Highlight Color: Lighter blonde highlights may fade faster and show brassiness sooner, while darker highlights (like caramel or honey) tend to last longer.

To make your Brown Blonde Highlights last longer, consider the following tips:
- Use sulfate-free, color-safe shampoos and conditioners.
- Apply toners or glosses every 1-2 weeks to maintain vibrancy and prevent brassiness.
- Limit washing frequency and use dry shampoo when possible.
- Protect your hair from heat styling tools by using heat protectant sprays.
- Avoid chlorine and harsh chemicals, especially if you swim frequently.

With proper care, your Brown Blonde Highlights can stay vibrant and fresh for several weeks, giving you a sun-kissed look without frequent salon visits.