Austin isn't the only place where home prices are on the rise. Nationally, the median home price will rise $6,275 next year, according to a new study from Zillow. In turn, prospective homebuyers will need to save a good chunk of change more to reach their goal of a 20 percent down payment.

Zillow says that nationally, homebuyers will need to save an additional $105 a month — $1,260 over the next year — to account for how much a 20 percent down payment will cost in 2018. The figure is higher in a couple hot Texas markets.

In the Austin-Round Rock metro area, the median home value is projected to be $283,871 by September 2018, a 3.3 percent increase from the September 2017 value of $274,400. That means Austin-area buyers need to sock away $153 more a month to afford a 20 percent down payment of $56,774.

But that's not the highest increase in Texas. You'll find that in Dallas-Fort Worth, where the median home value will reach $224,675 in September 2018, an increase of 4.6 percent. Homebuyers will have to save an additional $165 a month to keep up with rising prices.

Things are more manageable elsewhere in the Lone Star State. San Antonians only need to save an extra $74 a month for a down payment of $31,403 on a $170,515 home. That price is up 2.7 percent year over year. Houston is in the same range, with a home value increase of 2.8 percent, to $187,259. Residents will need to save an additional $84 a month for a down payment of $37,452.

The highest per-month increase is found in San Jose, California, where future homebuyers need to save $599 more a month towards a whopping $217,687 down payment.