New Castle, CO climate
New Castle has cold, snowy winters and warm summers, with very little rain. A typical July afternoon reaches 90°, a January night drops to 14°, and about 39 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in New Castle feels like
Winter
Spring
Summer
Fall
New Castle weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 37° | 14° | 0.8" | 13.7" | 8 | 20° – 33° |
| February | 43° | 19° | 0.8" | 6.3" | 6 | 26° – 38° |
| March | 54° | 27° | 0.9" | 2.4" | 6 | 36° – 46° |
| April | 61° | 32° | 1.1" | 0.6" | 7 | 43° – 53° |
| May | 72° | 40° | 1.3" | 0 | 6 | 51° – 60° |
| June | 84° | 48° | 0.7" | 0 | 5 | 60° – 71° |
| July | 90° | 55° | 0.8" | 0 | 5 | 68° – 76° |
| August | 87° | 53° | 1.0" | 0 | 7 | 67° – 75° |
| September | 79° | 45° | 1.4" | 0 | 6 | 56° – 66° |
| October | 65° | 33° | 1.2" | 0.7" | 6 | 43° – 54° |
| November | 50° | 24° | 0.8" | 4.4" | 6 | 29° – 43° |
| December | 38° | 15° | 0.9" | 10.8" | 7 | 19° – 32° |
| Year | 63° | 34° | 11.8" | 38.9" | 75 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in New Castle
New Castle gets 12 inches of rain and melted snow a year. September is the wettest month and June the driest. Rain or snow falls on about 75 days a year.
About 142 frost-free days a year
In half of years the last 32° night comes by May 13 and the first one by October 3. That leaves about 142 frost-free days for gardens, shorter than 88% of U.S. towns.
Heating and cooling a home in New Castle
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In New Castle, 94% of that work is heating and 6% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How New Castle compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in New Castle averaged 1.7° warmer than the 1900s. The biggest change is in March (+3.2°). The shift is larger than in 80% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at New Castle’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. November swings the most: between 1991 and 2020 its average temperature ranged from 29° to 43°. August is the most reliable, staying within 8°.
Common questions about New Castle’s climate
What is the coldest month in New Castle?
January, with a typical high of 37° and a low of 14°.
What is the hottest month in New Castle?
July, with a typical high of 90° and a low of 55°. About 39 days a year reach 90°.
How much snow does New Castle get?
About 39 inches in a normal winter, most of it in January.
When is the first frost in New Castle?
In half of years the first 32° night comes by October 3, and the last spring frost by May 13.
What is the rainiest month in New Castle?
September, with 1.4 inches of rain and melted snow. The year totals 12 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for New Castle itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Glenwood Spgs #2, CO (12 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.