Snow Moon Camp Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Snow Moon Camp Observatory clear sky chart from 2005-11-06 to 2024-11-04.

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	12% 9% 4 9% 6% 5% 5% 4 6% 7% 32%	101194
	Night	11% 9% 4 9% 5% 5% 5% 4 6% 7% 35%	97767
Transparency	Day	43% 10% 13% 18% 12% 4	104910
	Night	40% 11% 14% 18% 13% 5%	102190
Seeing	Day	21% 18% 25% 19% 12% 5%	15127
	Night	19% 16% 22% 25% 16% 3	25183

By Month

Percentage Cloud Cover SE (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% 10% 6% 12% 5% 5% 4 4 6% 6% 30%	2836
	11th to 20th	Day	10% 10% 7% 14% 5% 6% 6% 5% 6% 4 27%	2840
	21st to end	Day	15% 14% 6% 9% 4 3 4 4 5% 4 32%	3124
February	1st to 10th	Day	12% 11% 4 10% 6% 6% 5% 4 5% 5% 32%	1710
	11th to 20th	Day	15% 12% 4 10% 5% 4 3 4 5% 5% 32%	1847
	21st to end	Day	17% 9% 3 10% 5% 4 3 4 5% 6% 33%	1570
March	1st to 10th	Day	17% 9% 3 8% 5% 5% 4 4 5% 5% 33%	3425
	11th to 20th	Day	11% 8% 3 7% 5% 4 4 3 4 6% 45%	3480
	21st to end	Day	17% 9% 3 7% 5% 4 4 4 5% 7% 36%	3815
April	1st to 10th	Day	10% 9% 4 7% 5% 4 5% 4 7% 7% 37%	2090
	11th to 20th	Day	15% 9% 3 7% 5% 4 4 3 5% 7% 38%	2275
	21st to end	Day	14% 10% 3 8% 5% 4 6% 3 5% 6% 36%	2470
May	1st to 10th	Day	14% 11% 5% 9% 6% 6% 5% 4 6% 6% 27%	4082
	11th to 20th	Day	15% 11% 4 10% 6% 6% 6% 4 6% 6% 24%	4081
	21st to end	Day	9% 6% 3 7% 6% 6% 6% 5% 8% 10% 33%	4476
June	1st to 10th	Day	11% 8% 2 9% 6% 7% 7% 6% 6% 9% 29%	2470
	11th to 20th	Day	8% 7% 3 9% 7% 7% 7% 6% 7% 9% 30%	2470
	21st to end	Day	9% 7% 3 9% 6% 7% 7% 6% 8% 8% 29%	2470
July	1st to 10th	Day	7% 6% 3 9% 7% 7% 8% 6% 8% 9% 30%	4120
	11th to 20th	Day	10% 8% 3 9% 7% 7% 7% 5% 7% 8% 29%	4120
	21st to end	Day	16% 10% 4 14% 9% 7% 7% 4 6% 6% 15%	4466
August	1st to 10th	Day	12% 8% 3 11% 8% 7% 7% 6% 8% 9% 21%	4104
	11th to 20th	Day	8% 8% 3 11% 7% 8% 8% 6% 8% 9% 25%	4044
	21st to end	Day	6% 5% 2 7% 6% 6% 5% 5% 7% 11% 40%	4300
September	1st to 10th	Day	11% 7% 3 8% 6% 7% 6% 4 6% 8% 34%	2090
	11th to 20th	Day	13% 10% 4 10% 6% 5% 6% 4 6% 7% 30%	2090
	21st to end	Day	15% 9% 4 7% 6% 5% 5% 4 5% 8% 32%	2090
October	1st to 10th	Day	14% 8% 2 7% 4 4 3 3 5% 7% 43%	2005
	11th to 20th	Day	12% 8% 2 7% 4 4 4 3 5% 5% 47%	1900
	21st to end	Day	12% 9% 3 7% 4 4 3 2 4 5% 46%	2090
November	1st to 10th	Day	9% 6% 3 7% 3 4 4 3 4 6% 50%	1837
	11th to 20th	Day	10% 7% 3 7% 5% 4 4 5% 5% 6% 44%	1710
	21st to end	Day	11% 9% 3 7% 5% 5% 3 3 5% 5% 43%	1710
December	1st to 10th	Day	16% 11% 6% 9% 5% 5% 5% 3 5% 5% 30%	1710
	11th to 20th	Day	13% 8% 6% 6% 5% 4 5% 4 6% 7% 37%	2153
	21st to end	Day	14% 8% 6% 10% 6% 5% 6% 5% 5% 6% 30%	3124
January	1st to 10th	Night	11% 13% 6% 11% 7% 6% 5% 5% 5% 5% 25%	4109
	11th to 20th	Night	10% 10% 4 13% 7% 6% 4 3 5% 6% 34%	4120
	21st to end	Night	14% 15% 5% 9% 5% 4 4 3 5% 5% 30%	4532
February	1st to 10th	Night	12% 9% 4 10% 6% 4 4 4 6% 6% 34%	2469
	11th to 20th	Night	17% 11% 4 8% 7% 6% 4 5% 5% 4 30%	2218
	21st to end	Night	14% 9% 4 11% 7% 5% 5% 4 5% 6% 30%	1884
March	1st to 10th	Night	19% 14% 4 12% 6% 5% 3 3 4 4 27%	3428
	11th to 20th	Night	11% 8% 3 10% 5% 4 4 4 5% 6% 42%	3480
	21st to end	Night	12% 7% 4 7% 5% 5% 4 3 5% 7% 40%	3817
April	1st to 10th	Night	10% 9% 4 8% 5% 4 3 4 5% 7% 38%	2090
	11th to 20th	Night	11% 9% 3 7% 4 4 5% 4 6% 6% 39%	1867
	21st to end	Night	12% 7% 3 7% 4 5% 4 3 5% 7% 41%	1710
May	1st to 10th	Night	14% 12% 4 9% 6% 5% 5% 4 5% 7% 28%	2813
	11th to 20th	Night	15% 13% 5% 9% 5% 5% 5% 4 5% 6% 28%	2812
	21st to end	Night	9% 8% 3 7% 6% 5% 5% 5% 8% 10% 35%	3079
June	1st to 10th	Night	7% 7% 3 7% 7% 5% 5% 6% 8% 11% 34%	1710
	11th to 20th	Night	7% 6% 2 6% 5% 5% 6% 4 9% 11% 38%	1710
	21st to end	Night	7% 8% 3 7% 7% 5% 5% 5% 8% 10% 37%	1710
July	1st to 10th	Night	5% 7% 3 9% 6% 7% 7% 5% 8% 10% 32%	2840
	11th to 20th	Night	8% 6% 3 7% 5% 4 6% 5% 8% 10% 39%	2840
	21st to end	Night	11% 12% 5% 12% 8% 7% 6% 5% 6% 7% 21%	3087
August	1st to 10th	Night	10% 8% 4 10% 7% 6% 6% 6% 7% 10% 26%	2825
	11th to 20th	Night	9% 9% 3 11% 6% 5% 5% 5% 7% 7% 32%	2785
	21st to end	Night	5% 4 2 5% 4 4 5% 4 6% 10% 51%	3305
September	1st to 10th	Night	10% 9% 3 7% 6% 5% 4 4 7% 6% 39%	2090
	11th to 20th	Night	13% 8% 3 9% 5% 4 4 3 6% 7% 37%	2090
	21st to end	Night	11% 9% 4 9% 6% 5% 5% 3 4 5% 39%	2090
October	1st to 10th	Night	13% 8% 3 7% 4 3 4 4 4 6% 44%	2174
	11th to 20th	Night	11% 8% 4 7% 4 4 3 3 5% 5% 45%	2280
	21st to end	Night	9% 9% 4 8% 3 4 4 3 5% 6% 46%	2508
November	1st to 10th	Night	10% 8% 2 8% 5% 4 4 4 4 5% 46%	2311
	11th to 20th	Night	11% 7% 3 7% 4 3 4 4 5% 7% 43%	2470
	21st to end	Night	11% 8% 3 9% 4 4 4 4 6% 5% 43%	2470
December	1st to 10th	Night	14% 11% 4 10% 6% 5% 5% 5% 4 6% 29%	2470
	11th to 20th	Night	14% 10% 5% 12% 5% 4 4 3 5% 5% 32%	3042
	21st to end	Night	13% 12% 7% 13% 6% 5% 6% 4 5% 7% 22%	4532

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	36% 11% 17% 14% 18% 4	2837
	11th to 20th	Day	42% 14% 13% 11% 17% 3	2840
	21st to end	Day	46% 7% 12% 15% 16% 3	3124
February	1st to 10th	Day	48% 9% 10% 14% 15% 3	1710
	11th to 20th	Day	49% 8% 10% 14% 15% 3	1857
	21st to end	Day	48% 8% 12% 14% 14% 5%	1570
March	1st to 10th	Day	43% 10% 12% 17% 13% 4	3425
	11th to 20th	Day	36% 8% 10% 23% 16% 7%	3480
	21st to end	Day	44% 7% 11% 23% 12% 3	3815
April	1st to 10th	Day	40% 8% 11% 21% 16% 3	2090
	11th to 20th	Day	42% 8% 11% 18% 17% 4	2275
	21st to end	Day	44% 10% 12% 21% 12% 2	2470
May	1st to 10th	Day	49% 13% 12% 18% 7% 1	4120
	11th to 20th	Day	52% 13% 11% 19% 5% 1	4085
	21st to end	Day	37% 13% 16% 20% 11% 3	4489
June	1st to 10th	Day	47% 12% 14% 17% 9% 1	2470
	11th to 20th	Day	45% 13% 14% 16% 11% 1	2470
	21st to end	Day	45% 13% 13% 17% 12% 1	2470
July	1st to 10th	Day	44% 14% 17% 16% 8% 1	4055
	11th to 20th	Day	47% 13% 18% 16% 5% 1	4051
	21st to end	Day	64% 11% 10% 11% 3 1	4324
August	1st to 10th	Day	52% 13% 16% 15% 3	4091
	11th to 20th	Day	45% 14% 17% 15% 6% 2	4083
	21st to end	Day	35% 11% 19% 27% 8% 1	4300
September	1st to 10th	Day	45% 9% 13% 17% 14% 3	2090
	11th to 20th	Day	50% 8% 11% 17% 14% 1	2090
	21st to end	Day	48% 8% 13% 15% 12% 4	2090
October	1st to 10th	Day	29% 8% 10% 16% 25% 12%	3330
	11th to 20th	Day	24% 6% 8% 22% 17% 21%	3140
	21st to end	Day	26% 8% 8% 26% 15% 17%	3428
November	1st to 10th	Day	33% 7% 9% 19% 26% 6%	1837
	11th to 20th	Day	35% 7% 11% 17% 24% 6%	1710
	21st to end	Day	38% 6% 11% 19% 22% 4	1710
December	1st to 10th	Day	50% 9% 9% 15% 13% 3	1710
	11th to 20th	Day	36% 9% 15% 15% 21% 4	2150
	21st to end	Day	45% 8% 12% 20% 14% 2	3124
January	1st to 10th	Night	39% 14% 19% 12% 10% 6%	4109
	11th to 20th	Night	41% 13% 9% 13% 17% 7%	4120
	21st to end	Night	48% 9% 9% 13% 15% 4	4532
February	1st to 10th	Night	43% 9% 12% 18% 16% 3	2469
	11th to 20th	Night	46% 10% 11% 15% 13% 5%	2219
	21st to end	Night	46% 11% 11% 15% 12% 4	1884
March	1st to 10th	Night	50% 11% 12% 12% 12% 3	3428
	11th to 20th	Night	33% 9% 13% 23% 12% 9%	3480
	21st to end	Night	40% 8% 11% 23% 13% 4	3817
April	1st to 10th	Night	39% 11% 13% 21% 14% 3	2090
	11th to 20th	Night	37% 10% 14% 19% 16% 5%	1867
	21st to end	Night	40% 9% 14% 24% 13% 1	1710
May	1st to 10th	Night	45% 15% 14% 20% 6% 1	2840
	11th to 20th	Night	46% 15% 14% 20% 5%	2813
	21st to end	Night	32% 19% 18% 21% 9% 1	3087
June	1st to 10th	Night	39% 14% 17% 20% 10% 1	1710
	11th to 20th	Night	33% 14% 21% 23% 8% 1	1710
	21st to end	Night	36% 14% 18% 19% 11% 3	1710
July	1st to 10th	Night	38% 17% 18% 19% 7% 1	2795
	11th to 20th	Night	34% 14% 26% 21% 4 1	2786
	21st to end	Night	54% 16% 14% 12% 3	2988
August	1st to 10th	Night	45% 15% 21% 14% 5%	2814
	11th to 20th	Night	39% 16% 20% 16% 7% 1	2812
	21st to end	Night	27% 9% 20% 33% 8% 3	3305
September	1st to 10th	Night	41% 10% 14% 18% 13% 4	2090
	11th to 20th	Night	44% 9% 13% 18% 15% 1	2090
	21st to end	Night	45% 7% 12% 20% 14% 2	2090
October	1st to 10th	Night	29% 11% 12% 17% 18% 14%	3629
	11th to 20th	Night	25% 7% 9% 18% 19% 21%	3779
	21st to end	Night	27% 8% 8% 22% 17% 17%	4120
November	1st to 10th	Night	36% 6% 12% 18% 22% 7%	2311
	11th to 20th	Night	35% 7% 10% 18% 21% 8%	2470
	21st to end	Night	37% 7% 9% 21% 21% 5%	2470
December	1st to 10th	Night	47% 11% 11% 15% 12% 4	2470
	11th to 20th	Night	42% 10% 13% 12% 18% 5%	3044
	21st to end	Night	49% 12% 12% 14% 11% 1	4532

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	37% 32% 23% 7% 1	270
	11th to 20th	Day	38% 26% 29% 6% 1	270
	21st to end	Day	33% 36% 23% 7% 1	297
February	1st to 10th	Day	31% 31% 28% 9% 1	270
	11th to 20th	Day	47% 31% 19% 3	270
	21st to end	Day	42% 31% 23% 4	225
March	1st to 10th	Day	30% 26% 27% 12% 4	450
	11th to 20th	Day	32% 30% 23% 12% 3 1	460
	21st to end	Day	29% 27% 26% 12% 4	506
April	1st to 10th	Day	27% 27% 26% 14% 6% 1	460
	11th to 20th	Day	27% 23% 24% 16% 9% 2	452
	21st to end	Day	24% 21% 28% 15% 9% 4	460
May	1st to 10th	Day	22% 22% 33% 11% 7% 5%	463
	11th to 20th	Day	20% 16% 28% 20% 10% 6%	487
	21st to end	Day	16% 12% 23% 24% 14% 11%	529
June	1st to 10th	Day	14% 11% 29% 25% 14% 7%	490
	11th to 20th	Day	8% 10% 29% 28% 19% 7%	490
	21st to end	Day	10% 12% 33% 25% 12% 8%	490
July	1st to 10th	Day	8% 6% 23% 30% 20% 12%	485
	11th to 20th	Day	8% 7% 19% 35% 22% 9%	484
	21st to end	Day	11% 5% 25% 26% 20% 12%	532
August	1st to 10th	Day	15% 7% 26% 24% 15% 13%	486
	11th to 20th	Day	10% 9% 23% 26% 23% 10%	479
	21st to end	Day	12% 4 20% 27% 21% 16%	539
September	1st to 10th	Day	12% 5% 19% 29% 24% 10%	490
	11th to 20th	Day	16% 8% 17% 26% 24% 9%	490
	21st to end	Day	23% 13% 21% 23% 15% 4	490
October	1st to 10th	Day	20% 13% 22% 21% 20% 4	490
	11th to 20th	Day	17% 21% 26% 20% 15% 2	490
	21st to end	Day	18% 22% 25% 23% 8% 4	539
November	1st to 10th	Day	18% 18% 30% 21% 11% 2	417
	11th to 20th	Day	24% 26% 29% 16% 4 1	270
	21st to end	Day	23% 25% 30% 17% 4 1	270
December	1st to 10th	Day	30% 29% 30% 10% 1	270
	11th to 20th	Day	29% 23% 34% 11% 2	270
	21st to end	Day	28% 27% 32% 8% 4 1	297
January	1st to 10th	Night	27% 28% 24% 17% 3	760
	11th to 20th	Night	28% 24% 26% 18% 4	760
	21st to end	Night	26% 27% 28% 17% 3	836
February	1st to 10th	Night	21% 25% 26% 25% 3	760
	11th to 20th	Night	32% 31% 23% 14% 1	743
	21st to end	Night	26% 28% 32% 13% 1	628
March	1st to 10th	Night	22% 25% 31% 18% 4	760
	11th to 20th	Night	25% 24% 27% 17% 7%	760
	21st to end	Night	20% 23% 31% 20% 6%	836
April	1st to 10th	Night	23% 22% 25% 23% 7%	760
	11th to 20th	Night	20% 20% 25% 22% 11% 1	711
	21st to end	Night	14% 19% 23% 32% 11% 1	570
May	1st to 10th	Night	17% 16% 28% 24% 13% 1	570
	11th to 20th	Night	15% 9% 25% 31% 17% 2	561
	21st to end	Night	12% 9% 18% 29% 25% 7%	617
June	1st to 10th	Night	9% 5% 21% 33% 27% 5%	570
	11th to 20th	Night	8% 6% 21% 26% 34% 5%	570
	21st to end	Night	8% 7% 19% 32% 31% 3	570
July	1st to 10th	Night	11% 3 14% 27% 40% 5%	555
	11th to 20th	Night	7% 4 11% 29% 41% 7%	552
	21st to end	Night	6% 6% 12% 30% 38% 9%	624
August	1st to 10th	Night	12% 4 14% 28% 37% 5%	567
	11th to 20th	Night	13% 5% 13% 29% 33% 7%	564
	21st to end	Night	11% 3 11% 30% 37% 8%	712
September	1st to 10th	Night	12% 7% 14% 29% 30% 7%	760
	11th to 20th	Night	20% 4 14% 27% 30% 5%	760
	21st to end	Night	21% 9% 15% 27% 25% 2	760
October	1st to 10th	Night	15% 14% 19% 23% 23% 6%	760
	11th to 20th	Night	18% 17% 21% 27% 14% 3	760
	21st to end	Night	20% 17% 22% 27% 12% 2	836
November	1st to 10th	Night	17% 15% 23% 29% 14% 2	755
	11th to 20th	Night	23% 16% 20% 30% 9% 1	760
	21st to end	Night	21% 19% 25% 24% 10% 1	760
December	1st to 10th	Night	25% 22% 25% 21% 7%	760
	11th to 20th	Night	23% 23% 24% 24% 5% 1	760
	21st to end	Night	28% 20% 26% 22% 4	836

Page generated at 2024-11-01 22:47:52. Version ac07

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