Well during the closing process someone turned off the heat and knowing there were some leaks in the roof we saw that the temperature fluctuations caused the moisture in the house to expand and contract to cause our plaster to crumble whenever touched.

Vacancy, property repairs and owner paid utilities are additional required factors but can fluctuate throughout any given year based on market conditions, property age and configuration and tenant mix. 

The rates fluctuate with the seasons so is my best bet to just estimate an average?

You'll have other items to watch out for, especially how you're going to hedge currency fluctuation, financing hurdles (assuming you're a non-US citizen), etc.

It's not somewhere like Houston or any of those, but it's better than the stable midwestern markets which typically don't fluctuate much one way or the other.

Leadership changes.So, not only are you subject to currency fluctuations, but you're also at the whim of a government that may change the rules to suit their convenience (like Cristina Fernández de Kirchner in Argentina attempted to drastically raise taxes on farms to make up for a budget shortfall) or even completely change (Egypt, Tunsia, and I'm pretty sure we've not seen the last of that.)The countries you mention are more stable, but all have various issues.

Costs fluctuate with area but $70k is really high for a rehab.  

There is the lowest unemployment in the state, good wages, lots of jobs in transportation, 2 Amazon facilities, Overstock, Whirlpool, Hershey Park, and the largest growth in the state with a stable economy, not subject to market fluctuations.

Your USD debt may remain neutral based on currency fluctuations but as the peso weakens against the US dollar, your asset is worth less in real terms (USD).

Pete:Ours will fluctuate depending on whether we are shopping or not ... or, more correctly, whether we are finding anything worth purchasing when shopping.However, after an acquisition spree - and taking advantage of a little forced appreciation - we try to work the portfolio LTV back down 50% (or less) ... while keeping the equity easily accessible if we were to need it.