This indicator measures the number of frost days for 30 sites across Aotearoa New Zealand from at least 1972 to 2022.
The number of frost days changes from year to year in response to variable weather patterns, and their occurrence is also influenced by climate change. Climate models project we may experience fewer cold and more warm extremes in the future. Changes in the number and timing of frost days can affect agriculture, horticulture, and viticulture, for example, by damaging and destroying crops at sensitive growth stages.
Variables:
site: Site the NIWA climate stations represent.
year: Given year the number of frost days are calculated for.
Frost days: Total number of frost days are year as defined when the air temperature is below zero at 1.2m off the ground.
first_frost: The first day are recorded in a given year.
last_frost: The last days are recorded in a given year.
lat: Approximate latitude of site location.
lon: Approximate longitude of site location.
site_simple: Site the NIWA climate stations represent.
References:
Hutchinson, G. K., Richards, K., & Risk, W. H. (2000). Aspects of accumulated heat patterns (growing-degree days) and pasture growth in Southland. Proceedings of the New Zealand Grassland Association, 62, 81–85. https://doi.org/10.33584/jnzg.2000.62.2396
Macara, G., Nichol, D., Liley, B., & Noll, B. (2023). Ministry for the Environment Atmosphere and Climate Report 2023: Updated Datasets supplied by NIWA (NIWA Client Report No. 2023072WN). https://environment.govt.nz/publications/atmosphere-and-climate-indicators-2023-updated-datasets
Macara, G., & Tait, A. (2015). Infilling of missing climate data: temperature, rainfall and wind (NIWA Client Report No. WLG2015-33). https://data.mfe.govt.nz/document/21253-macara-g-tait-a-2015-infilling-of-missing-climate-data-for-the-2015-environmental-synthesis-report-temperature-rainfall-and-wind/
Mastrandrea, M. D., Field, C. B., Stocker, T. F., Edenhofer, O., Ebi, K. L., Frame, D. J., Held, H., Kriegler, E., Mach, K. J., Matschoss, P. R., Plattner, G.-K., Yohe, G. W., & Zwiers, F. W. (2010). Guidance Note for Lead Authors of the IPCC Fifth Assessment Report on Consistent Treatment of Uncertainties. Intergovernmental Panel on Climate Change (IPCC). https://www.ipcc.ch/site/assets/uploads/2018/05/uncertainty-guidance-note.pdf
