Southwest Airlines occasionally offers sales with one-way flights as low as $39, but there is no mention of $49 flights specifically. These sales are often limited-time and have restrictions like advance purchase requirements, limited seats, and blackout dates. 

Here's a breakdown of what to expect from such sales: 

• Limited Time: These sales are typically short-lived, so it's crucial to book quickly once you find a suitable fare.

• Restrictions: There are often restrictions on the days you can fly (e.g., Tuesdays, Wednesdays, Saturdays are usually cheaper), and blackout dates may apply.

• Advance Purchase: You usually need to book a certain number of days in advance (e.g., 21 days).

• Specific Markets: The sale may only apply to select routes or destinations.

• Seats are Limited: Not all seats on all flights will be available at the sale price.

• Additional Fees: Be aware that additional fees may apply, even with the sale price.

To find these deals:

• Check Southwest's Website:
  Regularly visit the Southwest Airlines website and sign up for their email list to receive notifications about sales. 

• Use the Low Fare Calendar:
  Southwest's low fare calendar can help you find the cheapest days to fly within a specific route and timeframe. 

Be Flexible:
If you have flexibility in your travel dates and destination, you're more likely to find a good deal.