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Castries vs Boulder
Comparing Castries change · Boulder change
Castries is the warmer of the two — about 17°C on the annual average; Castries is the wetter, with 1604 mm more rain a year.
How the seasons compare
The differences between Castries and Boulder, in everyday terms.
Summers
Boulder has hotter summers
Castries: Warm
Boulder: Hot
Winters
Castries has far milder winters
Castries: Stays warm
Boulder: Very cold
Rain & snow
Castries is much wetter
Castries: Very wet
Boulder: Fairly dry
Sky
Similar amounts of sun
Castries: Fairly sunny
Boulder: Partly cloudy
Month-by-month charts
Temperature
Castries is the warmer of the two — about 17°C on the annual average.
Precipitation
Castries is the wetter — about 1604 mm more across the year.
Clear skies
The two cities see a similar amount of sun.
Exact monthly numbers
Tap a metric to open its full table. Desktop shows all twelve months; on a phone each metric splits into Jan–Jun and Jul–Dec.
Avg high (°C) Castries runs higher most of the year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Castries | 27 | 27 | 27 | 28 | 28 | 28 | 28 | 29 | 29 | 29 | 28 | 27 |
| Boulder | 7 | 8 | 13 | 17 | 22 | 29 | 32 | 31 | 27 | 19 | 12 | 7 |
| Difference | -20 | -19 | -14 | -10 | -6 | +1 | +4 | +2 | -2 | -10 | -16 | -21 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Castries | 27 | 27 | 27 | 28 | 28 | 28 |
| Boulder | 7 | 8 | 13 | 17 | 22 | 29 |
| Difference | -20 | -19 | -14 | -10 | -6 | +1 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Castries | 28 | 29 | 29 | 29 | 28 | 27 |
| Boulder | 32 | 31 | 27 | 19 | 12 | 7 |
| Difference | +4 | +2 | -2 | -10 | -16 | -21 |
Avg low (°C) Castries runs higher most of the year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Castries | 26 | 25 | 25 | 26 | 27 | 27 | 27 | 28 | 28 | 28 | 27 | 26 |
| Boulder | -9 | -8 | -3 | 1 | 6 | 11 | 15 | 14 | 9 | 2 | -4 | -9 |
| Difference | -34 | -33 | -28 | -25 | -21 | -16 | -13 | -14 | -19 | -26 | -31 | -35 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Castries | 26 | 25 | 25 | 26 | 27 | 27 |
| Boulder | -9 | -8 | -3 | 1 | 6 | 11 |
| Difference | -34 | -33 | -28 | -25 | -21 | -16 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Castries | 27 | 28 | 28 | 28 | 27 | 26 |
| Boulder | 15 | 14 | 9 | 2 | -4 | -9 |
| Difference | -13 | -14 | -19 | -26 | -31 | -35 |
Precipitation (mm) Castries runs higher most of the year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Castries | 113 | 76 | 66 | 90 | 114 | 134 | 216 | 291 | 224 | 246 | 243 | 149 |
| Boulder | 11 | 11 | 25 | 45 | 60 | 36 | 44 | 45 | 30 | 26 | 18 | 9 |
| Difference | -103 | -65 | -41 | -45 | -54 | -98 | -172 | -246 | -194 | -220 | -225 | -140 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Castries | 113 | 76 | 66 | 90 | 114 | 134 |
| Boulder | 11 | 11 | 25 | 45 | 60 | 36 |
| Difference | -103 | -65 | -41 | -45 | -54 | -98 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Castries | 216 | 291 | 224 | 246 | 243 | 149 |
| Boulder | 44 | 45 | 30 | 26 | 18 | 9 |
| Difference | -172 | -246 | -194 | -220 | -225 | -140 |
Snowfall (cm)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Castries | — | — | — | — | — | — | — | — | — | — | — | — |
| Boulder | 13 | 13 | 15 | 8 | 1 | 0 | 0 | 0 | 1 | 8 | 15 | 13 |
| Difference | — | — | — | — | — | — | — | — | — | — | — | — |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Castries | — | — | — | — | — | — |
| Boulder | 13 | 13 | 15 | 8 | 1 | 0 |
| Difference | — | — | — | — | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Castries | — | — | — | — | — | — |
| Boulder | 0 | 0 | 1 | 8 | 15 | 13 |
| Difference | — | — | — | — | — | — |
Cloud cover (%) Boulder runs higher most of the year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Castries | 38 | 39 | 42 | 49 | 52 | 59 | 50 | 46 | 51 | 51 | 46 | 41 |
| Boulder | 57 | 57 | 56 | 59 | 58 | 49 | 50 | 50 | 43 | 46 | 51 | 55 |
| Difference | +19 | +18 | +14 | +10 | +6 | -10 | — | +4 | -8 | -5 | +5 | +15 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Castries | 38 | 39 | 42 | 49 | 52 | 59 |
| Boulder | 57 | 57 | 56 | 59 | 58 | 49 |
| Difference | +19 | +18 | +14 | +10 | +6 | -10 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Castries | 50 | 46 | 51 | 51 | 46 | 41 |
| Boulder | 50 | 50 | 43 | 46 | 51 | 55 |
| Difference | — | +4 | -8 | -5 | +5 | +15 |
Relative humidity (%) Castries runs higher most of the year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Castries | 76 | 75 | 75 | 76 | 77 | 79 | 79 | 79 | 79 | 79 | 79 | 77 |
| Boulder | 56 | 56 | 52 | 50 | 50 | 42 | 43 | 44 | 43 | 47 | 52 | 57 |
| Difference | -20 | -19 | -23 | -26 | -28 | -36 | -36 | -35 | -36 | -32 | -27 | -20 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Castries | 76 | 75 | 75 | 76 | 77 | 79 |
| Boulder | 56 | 56 | 52 | 50 | 50 | 42 |
| Difference | -20 | -19 | -23 | -26 | -28 | -36 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Castries | 79 | 79 | 79 | 79 | 79 | 77 |
| Boulder | 43 | 44 | 43 | 47 | 52 | 57 |
| Difference | -36 | -35 | -36 | -32 | -27 | -20 |
How both climates are changing
Both cities are warming. Each city has its own warming trend; see its trends page for the year-by-year detail. Castries trends → · Boulder trends →
Boulder from Cfa to BSk.
Methodology & sources
Castries
Temperature — modelled for this location from ERA5-Land reanalysis, a ~9 km global grid, because no long-record weather station is close enough to use.
Precipitation — 1991–2020 normals computed from 10 years of daily observations at LE Lamentin, a weather station, about 66 km from the city centre. The underlying daily records come from NOAA's global station network.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.
Boulder
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Brighton 3 SE (NOAA GHCN station USC00050950), about 38 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.
← change Castries · change Boulder → · Castries page · Boulder page