When planning a short hike or longer traverse in the future you need to understand whether you are choosing the right season and what weather you are likely to encounter: temperature (day, night), precipitation (rain >0, snow <0). We can also look at existing snow cover covered in this post). Weather is your most important adversary at higher altitudes. Weather forecast is usually short term and not precise further into the future. A better approach is to look at historical monthly weather data to make a more informed decision. Climate is also interconnected with the geography and eco-regions discussed in the previous chapter 8. We will be using weather data from:
- WorldClim (worldclim.org) provides historical climate and monthly weather data enabling us to plan global traverses during the right seasons
Contents
- World Clim
- Map Layers
- Temperatures
- Precipitation
- Planning a cycle trip in Europe
World Clim
WorldClim is a database of high spatial resolution global weather and climate data. These data can be used for mapping and spatial modeling. It includes historical climate data, bioclimatic variables and monthly weather data including temperature and precipitation. Download 5min resolution data for 2020-2024 for:
- Average minimum monthly temperature
- Average maximum monthly temperature
- Average monthly precipitation
Map Layers
We will be using base layers from Natural Earth (chapter 8) – countries, rivers and hill shading to display a color neutral base map that allows us to understand the geopolitical boundaries and topography of the region:
The data downloaded from WorldClim has data sets for individual months over 4 years. Let’s say we wish to plan a traverse in September in Central/Southeast Asia and therefore wish to understand the climate. Import the minimum temperature, maximum temperature and precipitation for September from 2024 (recent year) as three raster layers in GIS. By default each raster has gray-scale values between min (black) and max (white).
Precipitation
Let’s render the data in a more comprehensive manner. For precipitation (rain, snow fall) let’s use a singleband pseudocolor. Blue color discrete blue ramp with 13 equal intervals in 20mm steps:
This gives us an excellent view on the rainfall during September across the mountains of central and Southeast Asia. We see significant rainfall in Jammu, Himachal, Uttarakhand, Nepal and Arunachal. Dry weather in Kashmir, Ladakh and Bhutan.
Temperature
To understand the weather we can look at the average min (night) and max (day) temperatures for the region. For temperature use a 15 equal interval Turbo color ramp in 5 degree steps:
The minimum temperature for April raster layer now gives a clear view on the night temperature range across the region:
Zoom into any region and overlay the hiking routes to get a clear overview of the minimum temperatures across your planned traverse for the month of April. Weather data is shown at 5min (9km) resolution. You can also download the larger data set showing a 2.5m (4.5km) resolution. Say we plan the Trans Uttarakhand traverse in April we can expect an average night temperature around 10-15C with a few sections in the 5-10C range. Temperatures are sub zero (blue) for the higher altitude routes in Uttarakhand.
Similar rendering can be done for the maximum (mid-day) temperature showing an average of 15-20C with some 20-25C sections for the Trans Uttarakhand traverse. For the high routes we see 0-5C on the approach and -5-0C on the passes. Resolution shown below is 2.5min comparably more clear then the 5min data above.
Zooming out for the entire region we can see:
- Hot day temperatures in the Indian plains and Tarim basin in Xiang province of China
- Very hot weather in Punjab/Pakistan and Rajestan/India
- Moderate temperatures across the Himalayas, Karakoram, Hindu Kush, Pamir and Tian Shan mountain ranges
Planning a cycling trip in Europe
Last summer I did 4000km of cycling in Europe along the Mediterranean – the EuroVelo 8 route. Next January I plan to continue. I am a bit concerned of cycling in Europe in winter so I bring up the day-temperatures for January in order to finalize a suitable route:
I was considering the EuroVelo 1 which goes from Belgium to Germany, Switzerland and Italy. Day-time temperatures are fairly chill: 5-10 in Belgium and North Italy, 0-5C in Germany, -5-0C in Switzerland. Not really inviting to ride on a cycle. Similar night temperatures while camping are cold in January 0-5C in Belgium and South Italy, -5-0C in South Belgium, Germany and North Italy.
Another option would be to continue EuroVelo 8 along the Mediterranean coastline from France to Spain to Portugal. Day-time temperatures are pleasant at 10-15C in France and 15-20C in Spain and Portugal and nights ok at 5-10C along the coastal region so camping would be fine with proper sleeping bags. Inland temperatures are dropping to 0-5C. Next thing to look at is rainfall:
Here we see that we were about to make a mistake cycling through Portugal which receives more rainfall in January. Change of plan: in Gibraltar I will take a ferry to jump to Morocco (Africa) and follow the Mediterranean coastline via Algeria and Tunisia taking another ferry to Sicilia and South Italy. Day temperatures remain pleasant at 15-20C and nights at 5-10C across this entire section.