Coarsegold
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coarsegold clear sky chart from 2005-11-06 to 2025-03-27.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	7% 3 1 3 2 2 3 2 4 5% 68%	112897
	Night	9% 3 1 3 2 2 3 2 4 5% 65%	115272
Transparency	Day	20% 4 8% 17% 25% 26%	112647
	Night	22% 4 9% 19% 24% 22%	115112
Seeing	Day	8% 8% 25% 35% 19% 5%	15704
	Night	9% 2 13% 37% 32% 7%	25309

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 6% 2 4 3 3 3 3 5% 8% 51%	3639
	11th to 20th	Day	12% 4 2 6% 4 4 3 3 3 4 56%	3935
	21st to end	Day	15% 5% 2 5% 4 4 4 3 6% 7% 46%	4510
February	1st to 10th	Day	18% 6% 1 4 3 3 3 3 4 6% 49%	1881
	11th to 20th	Day	14% 6% 1 5% 4 3 3 3 6% 7% 48%	1950
	21st to end	Day	17% 7% 2 6% 3 3 4 4 4 5% 46%	1650
March	1st to 10th	Day	15% 10% 3 7% 4 4 5% 4 6% 8% 33%	3238
	11th to 20th	Day	11% 5% 1 4 3 2 3 3 4 6% 59%	3549
	21st to end	Day	18% 7% 2 6% 3 3 5% 4 5% 7% 41%	4156
April	1st to 10th	Day	12% 5% 2 4 4 3 3 2 4 6% 56%	2280
	11th to 20th	Day	11% 5% 2 4 3 3 2 3 5% 6% 57%	2249
	21st to end	Day	8% 4 1 4 3 3 3 3 4 6% 61%	2280
May	1st to 10th	Day	5% 2 1 3 1 2 2 1 3 5% 75%	3888
	11th to 20th	Day	3 1 1 2 1 1 2 2 3 5% 79%	4119
	21st to end	Day	4 2 1 2 2 1 2 2 3 4 78%	4813
June	1st to 10th	Day	3 3 1 3 2 2 3 3 4 6% 71%	2660
	11th to 20th	Day	1 1 2 2 1 1 2 2 4 85%	2660
	21st to end	Day	2 1 2 1 1 2 1 2 3 85%	2660
July	1st to 10th	Day	1 1 1 1 1 1 2 92%	4420
	11th to 20th	Day	1 1 1 1 2 2 2 3 3 84%	4420
	21st to end	Day	1 1 1 1 1 1 1 2 2 87%	4528
August	1st to 10th	Day	2 2 1 1 1 1 1 1 2 3 85%	3914
	11th to 20th	Day	1 1 1 1 1 1 1 2 91%	3724
	21st to end	Day	1 1 1 1 1 1 1 2 2 89%	4180
September	1st to 10th	Day	2 1 1 1 1 1 1 2 2 88%	2280
	11th to 20th	Day	2 2 1 2 1 2 2 2 3 4 81%	2235
	21st to end	Day	2 2 1 1 1 1 1 2 3 3 82%	2090
October	1st to 10th	Day	3 2 1 2 2 1 2 3 3 4 78%	3283
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 3 79%	3161
	21st to end	Day	4 2 1 4 3 3 3 2 4 6% 68%	3427
November	1st to 10th	Day	8% 3 1 3 4 3 3 2 5% 7% 60%	1764
	11th to 20th	Day	8% 3 1 4 3 2 2 3 5% 7% 62%	1800
	21st to end	Day	11% 5% 1 3 3 3 4 3 3 6% 58%	1800
December	1st to 10th	Day	8% 3 2 3 3 3 4 4 5% 5% 59%	2722
	11th to 20th	Day	20% 7% 2 6% 4 4 3 3 4 7% 42%	3028
	21st to end	Day	17% 6% 3 6% 4 4 5% 4 6% 9% 37%	4004
January	1st to 10th	Night	11% 6% 2 4 3 3 3 3 5% 7% 52%	6306
	11th to 20th	Night	14% 5% 2 4 3 3 3 3 4 5% 56%	6034
	21st to end	Night	16% 6% 2 5% 3 3 3 3 4 6% 50%	6468
February	1st to 10th	Night	17% 6% 2 4 2 2 3 3 4 6% 52%	2516
	11th to 20th	Night	15% 4 1 4 2 2 3 3 5% 7% 54%	2338
	21st to end	Night	15% 7% 2 5% 3 2 3 3 4 5% 52%	1980
March	1st to 10th	Night	19% 6% 2 5% 3 4 4 3 6% 6% 41%	3856
	11th to 20th	Night	12% 4 1 3 2 2 2 2 4 6% 60%	3647
	21st to end	Night	20% 6% 1 4 3 3 3 3 5% 6% 47%	3633
April	1st to 10th	Night	11% 5% 1 4 2 2 2 2 5% 6% 60%	1900
	11th to 20th	Night	8% 4 1 4 3 3 3 3 4 5% 64%	1879
	21st to end	Night	6% 3 1 2 2 3 3 2 4 5% 69%	1900
May	1st to 10th	Night	4 2 1 2 2 1 1 2 3 5% 78%	3087
	11th to 20th	Night	3 1 1 2 1 1 1 2 3 5% 80%	2779
	21st to end	Night	3 1 2 1 1 2 1 2 3 84%	2762
June	1st to 10th	Night	3 2 1 2 2 2 2 2 3 6% 74%	1520
	11th to 20th	Night	1 1 1 1 1 2 2 3 87%	1520
	21st to end	Night	1 1 1 1 1 1 1 2 3 88%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 94%	2540
	11th to 20th	Night	2 2 1 3 1 2 2 1 3 4 80%	2540
	21st to end	Night	1 1 1 1 1 2 2 2 3 85%	3029
August	1st to 10th	Night	1 1 1 2 1 2 2 1 3 4 83%	3029
	11th to 20th	Night	1 1 1 1 1 1 2 92%	3126
	21st to end	Night	2 1 1 1 1 1 1 1 2 89%	3498
September	1st to 10th	Night	1 1 1 1 1 1 1 2 90%	1900
	11th to 20th	Night	2 2 1 2 1 1 2 1 2 4 83%	1943
	21st to end	Night	2 1 1 2 1 1 2 1 2 3 84%	2090
October	1st to 10th	Night	2 2 1 2 1 1 2 1 2 4 82%	3693
	11th to 20th	Night	2 1 2 1 1 2 2 2 4 82%	3777
	21st to end	Night	4 2 1 3 2 2 2 1 3 5% 75%	4141
November	1st to 10th	Night	9% 3 1 3 2 2 2 2 4 7% 65%	2535
	11th to 20th	Night	7% 3 1 4 2 2 3 2 5% 6% 65%	2600
	21st to end	Night	10% 4 1 3 2 3 3 3 5% 6% 59%	2600
December	1st to 10th	Night	8% 3 1 4 2 3 3 3 4 6% 62%	4458
	11th to 20th	Night	20% 6% 2 5% 3 2 3 3 6% 9% 41%	5176
	21st to end	Night	14% 6% 3 8% 5% 5% 6% 4 8% 8% 33%	6952

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	28% 7% 23% 22% 15% 4	3639
	11th to 20th	Day	32% 7% 8% 13% 23% 17%	3935
	21st to end	Day	35% 8% 11% 14% 25% 7%	4510
February	1st to 10th	Day	36% 6% 9% 23% 19% 7%	1881
	11th to 20th	Day	34% 6% 11% 25% 18% 6%	1960
	21st to end	Day	39% 7% 11% 23% 17% 2	1650
March	1st to 10th	Day	43% 11% 14% 16% 14% 3	3238
	11th to 20th	Day	25% 7% 14% 32% 13% 10%	3549
	21st to end	Day	37% 11% 16% 21% 13% 3	4156
April	1st to 10th	Day	30% 4 12% 27% 19% 7%	2280
	11th to 20th	Day	28% 5% 11% 27% 22% 8%	2252
	21st to end	Day	23% 6% 11% 29% 26% 5%	2280
May	1st to 10th	Day	14% 3 8% 28% 32% 15%	3888
	11th to 20th	Day	10% 3 7% 24% 42% 14%	4122
	21st to end	Day	11% 3 6% 29% 41% 9%	4814
June	1st to 10th	Day	14% 5% 10% 20% 32% 18%	2660
	11th to 20th	Day	6% 2 5% 17% 40% 30%	2660
	21st to end	Day	8% 2 2 8% 31% 49%	2660
July	1st to 10th	Day	3 1 1 4 14% 77%	4351
	11th to 20th	Day	7% 2 2 5% 16% 67%	4345
	21st to end	Day	5% 2 2 6% 27% 57%	4385
August	1st to 10th	Day	8% 1 2 6% 27% 56%	3899
	11th to 20th	Day	4 1 1 5% 25% 65%	3760
	21st to end	Day	5% 1 3 6% 29% 55%	4179
September	1st to 10th	Day	6% 1 2 7% 29% 54%	2280
	11th to 20th	Day	9% 2 4 20% 37% 28%	2235
	21st to end	Day	8% 2 3 17% 37% 32%	2090
October	1st to 10th	Day	12% 2 4 10% 20% 52%	3283
	11th to 20th	Day	12% 2 4 21% 41% 21%	3161
	21st to end	Day	18% 3 5% 16% 39% 19%	3427
November	1st to 10th	Day	24% 5% 12% 20% 24% 16%	1764
	11th to 20th	Day	23% 4 13% 27% 25% 9%	1800
	21st to end	Day	29% 3 9% 18% 27% 13%	1800
December	1st to 10th	Day	25% 4 8% 27% 25% 11%	2722
	11th to 20th	Day	43% 4 11% 16% 21% 5%	3028
	21st to end	Day	41% 9% 18% 23% 7% 2	4004
January	1st to 10th	Night	28% 8% 20% 23% 16% 4	6306
	11th to 20th	Night	31% 5% 12% 14% 28% 10%	6034
	21st to end	Night	35% 6% 9% 20% 22% 9%	6468
February	1st to 10th	Night	35% 5% 9% 23% 20% 8%	2516
	11th to 20th	Night	29% 6% 11% 27% 21% 7%	2339
	21st to end	Night	35% 4 12% 26% 17% 5%	1980
March	1st to 10th	Night	39% 9% 13% 18% 17% 3	3856
	11th to 20th	Night	26% 5% 11% 34% 14% 9%	3647
	21st to end	Night	37% 7% 16% 24% 13% 3	3633
April	1st to 10th	Night	26% 5% 15% 27% 20% 8%	1900
	11th to 20th	Night	23% 5% 12% 30% 22% 8%	1879
	21st to end	Night	19% 4 13% 31% 28% 4	1900
May	1st to 10th	Night	11% 4 8% 32% 32% 12%	3087
	11th to 20th	Night	8% 2 6% 26% 43% 14%	2780
	21st to end	Night	9% 3 7% 28% 46% 8%	2762
June	1st to 10th	Night	14% 3 11% 22% 33% 18%	1520
	11th to 20th	Night	5% 3 4 18% 39% 31%	1520
	21st to end	Night	5% 2 3 8% 30% 52%	1520
July	1st to 10th	Night	2 1 1 3 15% 78%	2500
	11th to 20th	Night	11% 2 1 4 15% 66%	2492
	21st to end	Night	7% 2 2 6% 23% 60%	2934
August	1st to 10th	Night	9% 1 1 8% 24% 57%	3020
	11th to 20th	Night	4 1 2 4 19% 70%	3156
	21st to end	Night	7% 1 1 5% 27% 59%	3498
September	1st to 10th	Night	4 2 2 7% 27% 59%	1900
	11th to 20th	Night	9% 2 4 14% 42% 29%	1943
	21st to end	Night	8% 1 3 15% 39% 33%	2090
October	1st to 10th	Night	9% 2 3 10% 22% 53%	3693
	11th to 20th	Night	10% 2 4 22% 41% 21%	3777
	21st to end	Night	14% 2 3 20% 37% 24%	4141
November	1st to 10th	Night	21% 4 11% 24% 23% 17%	2535
	11th to 20th	Night	20% 4 12% 25% 25% 14%	2600
	21st to end	Night	26% 4 9% 21% 29% 11%	2600
December	1st to 10th	Night	24% 3 9% 29% 22% 13%	4458
	11th to 20th	Night	40% 4 14% 17% 20% 5%	5176
	21st to end	Night	44% 9% 15% 22% 7% 3	6952

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 9% 26% 27% 11% 4	200
	11th to 20th	Day	17% 6% 23% 32% 17% 6%	326
	21st to end	Day	17% 7% 23% 32% 16% 5%	440
February	1st to 10th	Day	21% 9% 26% 26% 13% 5%	441
	11th to 20th	Day	17% 10% 32% 27% 12% 2	495
	21st to end	Day	14% 12% 32% 30% 12%	414
March	1st to 10th	Day	17% 14% 29% 29% 9% 2	500
	11th to 20th	Day	19% 13% 30% 23% 13% 2	500
	21st to end	Day	17% 15% 31% 25% 11% 1	531
April	1st to 10th	Day	13% 16% 30% 25% 15% 1	460
	11th to 20th	Day	15% 16% 27% 29% 11% 2	452
	21st to end	Day	7% 13% 29% 31% 16% 4	460
May	1st to 10th	Day	7% 16% 36% 28% 11% 4	463
	11th to 20th	Day	8% 10% 30% 32% 15% 5%	488
	21st to end	Day	8% 10% 22% 38% 15% 6%	529
June	1st to 10th	Day	3 9% 27% 34% 21% 7%	490
	11th to 20th	Day	2 7% 28% 39% 17% 7%	490
	21st to end	Day	1 5% 24% 41% 21% 8%	490
July	1st to 10th	Day	1 1 19% 46% 24% 9%	486
	11th to 20th	Day	2 11% 47% 27% 13%	484
	21st to end	Day	1 1 16% 45% 27% 11%	531
August	1st to 10th	Day	3 2 20% 46% 19% 9%	487
	11th to 20th	Day	2 4 20% 45% 20% 10%	477
	21st to end	Day	2 2 17% 45% 25% 10%	539
September	1st to 10th	Day	2 4 19% 43% 26% 6%	490
	11th to 20th	Day	3 5% 28% 40% 21% 3	490
	21st to end	Day	2 7% 21% 44% 24% 3	490
October	1st to 10th	Day	3 6% 26% 36% 25% 4	490
	11th to 20th	Day	3 7% 24% 39% 24% 4	490
	21st to end	Day	5% 5% 22% 38% 26% 3	530
November	1st to 10th	Day	8% 7% 24% 28% 28% 5%	300
	11th to 20th	Day	6% 4 27% 34% 23% 6%	300
	21st to end	Day	13% 6% 23% 29% 23% 5%	300
December	1st to 10th	Day	13% 2 26% 31% 22% 6%	231
	11th to 20th	Day	16% 5% 24% 34% 16% 7%	200
	21st to end	Day	20% 8% 27% 26% 14% 6%	220
January	1st to 10th	Night	18% 2 18% 33% 21% 9%	800
	11th to 20th	Night	11% 4 19% 39% 22% 6%	800
	21st to end	Night	18% 3 15% 37% 22% 6%	880
February	1st to 10th	Night	20% 3 15% 36% 19% 7%	800
	11th to 20th	Night	16% 4 17% 33% 25% 7%	784
	21st to end	Night	18% 3 15% 43% 18% 3	660
March	1st to 10th	Night	18% 5% 16% 38% 19% 4	800
	11th to 20th	Night	14% 6% 16% 31% 27% 6%	800
	21st to end	Night	15% 3 18% 39% 23% 2	862
April	1st to 10th	Night	12% 5% 19% 38% 25% 2	760
	11th to 20th	Night	7% 5% 21% 38% 24% 5%	751
	21st to end	Night	7% 2 19% 38% 27% 6%	760
May	1st to 10th	Night	5% 5% 18% 42% 26% 5%	706
	11th to 20th	Night	5% 2 17% 43% 32% 2	533
	21st to end	Night	5% 2 15% 39% 35% 4	411
June	1st to 10th	Night	4 2 10% 44% 37% 3	380
	11th to 20th	Night	1 12% 44% 39% 3	380
	21st to end	Night	1 9% 38% 47% 4	380
July	1st to 10th	Night	5% 39% 53% 3	370
	11th to 20th	Night	3 1 2 38% 49% 7%	368
	21st to end	Night	1 6% 26% 54% 12%	570
August	1st to 10th	Night	2 1 6% 38% 46% 8%	670
	11th to 20th	Night	1 4 38% 49% 8%	752
	21st to end	Night	2 3 29% 57% 8%	836
September	1st to 10th	Night	1 1 5% 34% 50% 9%	760
	11th to 20th	Night	2 1 8% 39% 41% 10%	760
	21st to end	Night	3 1 7% 36% 46% 8%	760
October	1st to 10th	Night	5% 1 9% 43% 36% 6%	760
	11th to 20th	Night	5% 1 10% 38% 37% 10%	760
	21st to end	Night	5% 1 12% 35% 32% 15%	836
November	1st to 10th	Night	9% 3 11% 34% 32% 12%	780
	11th to 20th	Night	7% 2 16% 39% 29% 8%	800
	21st to end	Night	10% 2 15% 39% 27% 8%	800
December	1st to 10th	Night	15% 2 13% 39% 25% 6%	800
	11th to 20th	Night	20% 2 13% 39% 22% 5%	800
	21st to end	Night	20% 2 20% 36% 18% 4	880

Page generated at 2025-03-24 06:04:30. Version ac07

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