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 2024-10-20.

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 2 2 4 5% 68%	100918
	Night	9% 4 1 3 2 2 2 2 4 5% 65%	97990
Transparency	Day	20% 5% 8% 17% 24% 27%	100668
	Night	22% 5% 9% 19% 22% 22%	97830
Seeing	Day	8% 8% 24% 35% 19% 5%	15211
	Night	9% 2 12% 37% 32% 7%	24677

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	15% 8% 2 6% 4 4 4 4 6% 8% 40%	2539
	11th to 20th	Day	17% 6% 3 8% 5% 6% 5% 4 5% 6% 36%	2737
	21st to end	Day	20% 6% 2 6% 4 4 4 3 7% 9% 34%	3146
February	1st to 10th	Day	17% 5% 1 4 3 3 3 3 4 6% 49%	1786
	11th to 20th	Day	14% 6% 1 5% 4 3 3 3 5% 6% 49%	1850
	21st to end	Day	18% 7% 2 6% 3 3 4 4 4 5% 46%	1570
March	1st to 10th	Day	15% 10% 3 7% 4 4 5% 4 7% 8% 33%	3138
	11th to 20th	Day	10% 5% 1 4 3 2 3 2 4 6% 60%	3441
	21st to end	Day	18% 7% 2 6% 3 3 5% 4 5% 7% 40%	4085
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	4 3 1 3 2 2 3 2 3 4 73%	1967
	11th to 20th	Day	3 1 1 2 2 2 3 2 4 4 75%	1891
	21st to end	Day	6% 2 1 2 1 2 2 2 4 5% 72%	1972
November	1st to 10th	Day	9% 4 1 3 4 3 3 2 5% 7% 59%	1674
	11th to 20th	Day	8% 3 1 3 3 2 2 3 5% 6% 63%	1710
	21st to end	Day	10% 5% 1 3 3 3 4 3 3 6% 59%	1710
December	1st to 10th	Day	14% 4 2 3 4 3 4 3 4 6% 53%	1580
	11th to 20th	Day	24% 8% 2 6% 5% 4 3 2 3 6% 37%	1928
	21st to end	Day	13% 7% 4 6% 5% 4 5% 4 6% 9% 37%	2794
January	1st to 10th	Night	15% 8% 3 6% 3 3 3 3 5% 6% 46%	4406
	11th to 20th	Night	20% 7% 3 5% 4 4 4 4 6% 7% 38%	4225
	21st to end	Night	21% 7% 2 5% 4 3 4 3 5% 8% 39%	4521
February	1st to 10th	Night	16% 6% 2 4 2 2 3 3 4 6% 52%	2391
	11th to 20th	Night	14% 4 1 4 2 2 3 3 5% 7% 55%	2218
	21st to end	Night	16% 7% 2 5% 3 2 2 3 4 5% 51%	1884
March	1st to 10th	Night	20% 6% 2 5% 3 4 4 3 6% 6% 41%	3736
	11th to 20th	Night	12% 4 1 3 2 2 2 2 4 6% 62%	3535
	21st to end	Night	20% 6% 1 4 3 3 3 3 5% 6% 46%	3566
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	4 3 1 3 1 1 2 2 3 5% 75%	2209
	11th to 20th	Night	4 1 1 2 1 2 2 3 3 4 77%	2273
	21st to end	Night	5% 1 2 1 2 2 1 3 5% 79%	2384
November	1st to 10th	Night	9% 3 1 3 2 2 2 2 4 7% 64%	2405
	11th to 20th	Night	7% 3 1 3 2 2 2 2 5% 6% 66%	2470
	21st to end	Night	9% 4 1 3 2 3 3 3 5% 6% 60%	2470
December	1st to 10th	Night	14% 5% 2 5% 2 3 3 2 4 6% 54%	2597
	11th to 20th	Night	24% 6% 2 5% 3 3 3 3 5% 6% 39%	3276
	21st to end	Night	15% 6% 3 7% 5% 5% 5% 4 7% 7% 37%	4862

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	37% 10% 22% 20% 9% 2	2539
	11th to 20th	Day	46% 10% 12% 15% 10% 8%	2737
	21st to end	Day	42% 11% 16% 17% 11% 4	3146
February	1st to 10th	Day	35% 6% 9% 24% 18% 7%	1786
	11th to 20th	Day	33% 6% 10% 24% 19% 7%	1860
	21st to end	Day	39% 8% 11% 23% 18% 1	1570
March	1st to 10th	Day	43% 11% 14% 16% 14% 3	3138
	11th to 20th	Day	24% 7% 13% 32% 13% 10%	3441
	21st to end	Day	37% 11% 16% 21% 13% 3	4085
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	15% 4 6% 16% 27% 32%	1967
	11th to 20th	Day	13% 3 6% 22% 29% 27%	1891
	21st to end	Day	15% 3 7% 21% 30% 23%	1972
November	1st to 10th	Day	25% 6% 11% 19% 24% 16%	1674
	11th to 20th	Day	22% 4 13% 26% 26% 10%	1710
	21st to end	Day	29% 3 10% 19% 26% 14%	1710
December	1st to 10th	Day	32% 6% 12% 21% 19% 11%	1580
	11th to 20th	Day	50% 6% 9% 16% 13% 7%	1928
	21st to end	Day	40% 11% 17% 20% 8% 3	2794
January	1st to 10th	Night	35% 11% 19% 22% 12% 2	4406
	11th to 20th	Night	44% 7% 18% 14% 10% 7%	4225
	21st to end	Night	41% 8% 13% 21% 13% 4	4521
February	1st to 10th	Night	34% 5% 10% 23% 19% 9%	2391
	11th to 20th	Night	28% 6% 11% 27% 21% 7%	2219
	21st to end	Night	36% 4 12% 26% 17% 4	1884
March	1st to 10th	Night	39% 9% 14% 19% 17% 3	3736
	11th to 20th	Night	25% 5% 11% 34% 15% 10%	3535
	21st to end	Night	37% 7% 16% 24% 13% 3	3566
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	14% 3 6% 17% 26% 34%	2209
	11th to 20th	Night	12% 3 7% 20% 31% 27%	2273
	21st to end	Night	11% 2 5% 24% 31% 26%	2384
November	1st to 10th	Night	22% 4 11% 22% 24% 18%	2405
	11th to 20th	Night	20% 4 12% 26% 25% 14%	2470
	21st to end	Night	25% 4 9% 22% 29% 12%	2470
December	1st to 10th	Night	33% 5% 11% 21% 18% 13%	2597
	11th to 20th	Night	45% 5% 12% 16% 16% 6%	3276
	21st to end	Night	40% 11% 15% 20% 9% 4	4862

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	27% 7% 26% 26% 12% 4	180
	11th to 20th	Day	18% 6% 22% 31% 17% 6%	299
	21st to end	Day	18% 7% 21% 32% 16% 5%	407
February	1st to 10th	Day	20% 8% 26% 26% 15% 6%	406
	11th to 20th	Day	17% 10% 31% 28% 13% 2	455
	21st to end	Day	15% 13% 31% 30% 12% 1	382
March	1st to 10th	Day	17% 13% 29% 30% 9% 2	460
	11th to 20th	Day	17% 13% 29% 23% 14% 3	460
	21st to end	Day	18% 15% 31% 25% 9% 1	506
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 6% 25% 39% 23% 4	487
	21st to end	Day	6% 5% 21% 37% 28% 4	487
November	1st to 10th	Day	9% 6% 23% 29% 28% 6%	270
	11th to 20th	Day	6% 4 23% 36% 25% 7%	270
	21st to end	Day	11% 6% 21% 31% 26% 5%	270
December	1st to 10th	Day	14% 2 27% 30% 22% 5%	208
	11th to 20th	Day	15% 5% 24% 35% 14% 7%	180
	21st to end	Day	19% 8% 25% 26% 15% 7%	198
January	1st to 10th	Night	19% 2 16% 33% 21% 9%	760
	11th to 20th	Night	11% 4 17% 39% 23% 7%	760
	21st to end	Night	18% 2 14% 37% 22% 7%	836
February	1st to 10th	Night	19% 3 13% 38% 19% 7%	760
	11th to 20th	Night	15% 4 15% 33% 26% 7%	744
	21st to end	Night	19% 3 15% 41% 19% 4	628
March	1st to 10th	Night	19% 5% 15% 39% 19% 4	760
	11th to 20th	Night	14% 6% 15% 31% 29% 6%	760
	21st to end	Night	16% 3 18% 38% 23% 2	836
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%	758
	21st to end	Night	5% 1 11% 34% 33% 16%	792
November	1st to 10th	Night	9% 3 9% 34% 33% 12%	740
	11th to 20th	Night	7% 2 13% 40% 31% 8%	760
	21st to end	Night	10% 1 13% 39% 28% 9%	760
December	1st to 10th	Night	15% 2 13% 39% 24% 6%	760
	11th to 20th	Night	20% 2 12% 39% 22% 5%	760
	21st to end	Night	20% 2 18% 36% 19% 4	836

Page generated at 2024-10-17 10:09:42. Version ac07

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