Dreamcatcher Alpacas

Methodology: Local Alpaca Climate Guides

Updated 2026-10-02By the Dreamcatcher Alpacas editorial team

Data

  • U.S. county climate: NOAA NCEI nClimDiv county normals for 1991–2020 (monthly average high, low and mean temperature and precipitation). Virginia's independent cities and DC use the surrounding county.
  • Hawaii and international regions: Open-Meteo historical weather API (ERA5/ERA5-Land reanalysis), 2023–2024 daily data averaged by month.
  • Humidity: Open-Meteo 2024 daily mean relative humidity for a representative point in each state.
  • County boundaries and coordinates: U.S. Census Bureau 2020 Gazetteer.
  • Alpaca farms: OpenStreetMap contributors (ODbL), features whose names mention alpacas.
  • Selenium and meningeal worm: regional status from USDA/USGS forage selenium mapping and the published range of Parelaphostrongylus tenuis.

Formulas

  • Heat-stress index = average daily high (°F) + mean relative humidity (%). Under 120 comfortable; 120–150 caution; 150–180 high risk; over 180 dangerous. Mean humidity is used, which errs on the side of caution.
  • Hot days and frost nights are estimated from monthly averages assuming daily highs vary with a standard deviation of 6°F and lows of 7°F.
  • Barber pole worm months follow Gordon's bioclimatograph: average high ≥ 64.4°F (18°C) and rainfall ≥ 1.97 in (50 mm).
  • Shearing month: the first spring month with average lows of at least 38°F, moved earlier if highs reach 85°F.
  • Birthing window: months with average highs of 55–86°F, lows of at least 36°F and no high heat-stress risk; breeding month = birth month + 1 (≈335-day gestation).
  • Grazing months: average temperature ≥ 45°F with at least 0.8 in of rain, excluding hot dry months.
  • Hay estimate: 3.2 lb/day per adult when not grazing, 1 lb/day while grazing, in 50 lb bales.
  • Alpaca climate comfort score (0–100) deducts points for dangerous and high heat months, worm-season length, severe cold months, very wet or very dry climates and meningeal worm risk.
  • Köppen–Geiger class computed from the monthly normals (0°C threshold between C and D climates).

These guides describe the long-term average climate. Weather varies year to year — always watch the forecast and your animals. Found an error? Tell us.