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 2024-04-03.

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	13% 9% 4 8% 7% 4 6% 5% 6% 7% 33%	79228
	Night	11% 9% 4 8% 6% 4 5% 5% 6% 7% 35%	80915
Transparency	Day	45% 10% 12% 17% 13% 3	78951
	Night	41% 11% 13% 17% 14% 3	80711
Seeing	Day	21% 18% 25% 19% 12% 6%	14267
	Night	19% 16% 22% 24% 16% 3	24452

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% 9% 7% 11% 6% 4 5% 5% 6% 6% 30%	2836
	11th to 20th	Day	10% 10% 7% 13% 6% 5% 6% 6% 6% 4 27%	2840
	21st to end	Day	15% 14% 6% 8% 5% 3 4 5% 5% 4 32%	3124
February	1st to 10th	Day	13% 10% 5% 8% 7% 4 5% 5% 5% 6% 32%	1710
	11th to 20th	Day	16% 11% 5% 9% 7% 3 4 4 5% 5% 32%	1847
	21st to end	Day	17% 9% 4 9% 6% 3 4 4 5% 6% 33%	1570
March	1st to 10th	Day	13% 7% 3 8% 6% 3 5% 5% 5% 5% 40%	2080
	11th to 20th	Day	16% 10% 4 7% 7% 3 5% 4 5% 6% 32%	2090
	21st to end	Day	16% 11% 4 7% 6% 3 5% 4 5% 7% 32%	2299
April	1st to 10th	Day	10% 8% 5% 6% 6% 3 4 5% 6% 8% 38%	2002
	11th to 20th	Day	16% 8% 3 6% 5% 3 5% 4 5% 7% 38%	2153
	21st to end	Day	14% 9% 4 7% 6% 3 6% 5% 5% 6% 36%	2340
May	1st to 10th	Day	13% 9% 4 7% 6% 4 6% 6% 6% 7% 32%	2340
	11th to 20th	Day	17% 10% 4 8% 7% 4 6% 4 5% 6% 28%	2301
	21st to end	Day	13% 8% 4 6% 7% 4 7% 6% 7% 9% 29%	2531
June	1st to 10th	Day	12% 7% 3 8% 6% 5% 7% 7% 6% 9% 29%	2340
	11th to 20th	Day	9% 7% 3 8% 9% 5% 8% 7% 7% 9% 30%	2340
	21st to end	Day	9% 7% 3 7% 8% 5% 8% 8% 8% 8% 29%	2340
July	1st to 10th	Day	11% 8% 4 8% 9% 5% 7% 6% 8% 9% 25%	2340
	11th to 20th	Day	11% 8% 5% 8% 8% 6% 7% 7% 7% 8% 25%	2340
	21st to end	Day	12% 7% 4 10% 9% 5% 8% 6% 7% 8% 23%	2547
August	1st to 10th	Day	13% 8% 3 9% 9% 6% 7% 7% 7% 9% 22%	2327
	11th to 20th	Day	12% 9% 4 9% 9% 6% 8% 7% 7% 7% 24%	2303
	21st to end	Day	11% 7% 4 8% 8% 4 6% 6% 7% 9% 29%	2454
September	1st to 10th	Day	12% 7% 3 7% 7% 6% 6% 5% 6% 8% 33%	1980
	11th to 20th	Day	13% 9% 4 9% 7% 4 6% 5% 6% 7% 31%	1980
	21st to end	Day	14% 9% 4 6% 7% 3 5% 5% 5% 8% 33%	1980
October	1st to 10th	Day	14% 8% 3 6% 5% 3 4 4 5% 7% 42%	1900
	11th to 20th	Day	12% 7% 3 7% 5% 3 4 4 5% 5% 46%	1800
	21st to end	Day	13% 8% 3 7% 4 3 4 3 4 5% 44%	1980
November	1st to 10th	Day	9% 6% 3 6% 4 3 4 4 4 6% 51%	1807
	11th to 20th	Day	10% 6% 3 7% 5% 3 4 6% 5% 6% 45%	1710
	21st to end	Day	12% 9% 4 6% 5% 4 3 4 5% 6% 43%	1710
December	1st to 10th	Day	16% 11% 6% 8% 6% 4 5% 5% 5% 6% 30%	1710
	11th to 20th	Day	13% 8% 6% 6% 5% 3 5% 5% 6% 7% 37%	2153
	21st to end	Day	14% 8% 6% 8% 7% 4 6% 6% 6% 6% 30%	3124
January	1st to 10th	Night	11% 13% 6% 10% 8% 5% 6% 6% 5% 5% 25%	4109
	11th to 20th	Night	10% 9% 4 11% 8% 5% 4 5% 5% 6% 34%	4120
	21st to end	Night	14% 14% 6% 8% 6% 3 4 4 5% 5% 30%	4532
February	1st to 10th	Night	12% 9% 4 9% 7% 3 4 6% 6% 6% 34%	2469
	11th to 20th	Night	17% 10% 5% 7% 8% 4 5% 6% 5% 5% 30%	2218
	21st to end	Night	14% 9% 4 10% 8% 3 5% 5% 5% 6% 30%	1884
March	1st to 10th	Night	12% 8% 4 9% 7% 3 5% 5% 4 5% 38%	2100
	11th to 20th	Night	13% 10% 4 10% 7% 3 6% 5% 5% 6% 32%	2090
	21st to end	Night	12% 8% 5% 9% 7% 4 6% 4 5% 7% 35%	2299
April	1st to 10th	Night	11% 8% 4 7% 7% 3 4 5% 5% 8% 38%	2003
	11th to 20th	Night	11% 8% 3 6% 5% 3 6% 5% 6% 7% 40%	1769
	21st to end	Night	13% 7% 3 6% 5% 4 5% 4 5% 7% 41%	1620
May	1st to 10th	Night	14% 10% 4 6% 5% 3 5% 6% 5% 7% 35%	1620
	11th to 20th	Night	12% 7% 5% 7% 6% 4 6% 7% 6% 8% 33%	1592
	21st to end	Night	9% 9% 3 7% 6% 3 6% 6% 8% 10% 33%	1744
June	1st to 10th	Night	7% 6% 4 6% 7% 4 5% 8% 7% 11% 35%	1620
	11th to 20th	Night	7% 6% 3 5% 6% 4 6% 6% 8% 11% 39%	1620
	21st to end	Night	7% 7% 4 6% 7% 4 5% 6% 8% 10% 36%	1620
July	1st to 10th	Night	8% 8% 3 6% 6% 4 6% 5% 7% 11% 36%	1620
	11th to 20th	Night	9% 5% 2 6% 6% 3 7% 6% 9% 12% 35%	1620
	21st to end	Night	6% 6% 4 7% 7% 4 8% 7% 8% 10% 34%	1771
August	1st to 10th	Night	9% 7% 3 7% 8% 4 6% 6% 6% 10% 33%	1611
	11th to 20th	Night	11% 7% 3 8% 8% 4 5% 7% 7% 7% 33%	1598
	21st to end	Night	8% 6% 3 7% 6% 4 5% 5% 7% 11% 37%	1879
September	1st to 10th	Night	10% 8% 3 6% 7% 4 4 5% 7% 6% 39%	1980
	11th to 20th	Night	13% 8% 3 8% 6% 3 4 5% 5% 7% 38%	1980
	21st to end	Night	11% 9% 4 8% 6% 4 5% 4 4 5% 41%	1980
October	1st to 10th	Night	13% 7% 3 6% 5% 2 4 5% 4 7% 44%	2059
	11th to 20th	Night	12% 8% 4 6% 5% 3 4 3 5% 5% 44%	2160
	21st to end	Night	9% 9% 4 7% 5% 2 4 4 5% 6% 45%	2376
November	1st to 10th	Night	10% 7% 3 7% 6% 2 4 5% 4 6% 46%	2268
	11th to 20th	Night	11% 7% 4 7% 5% 2 5% 5% 5% 8% 43%	2470
	21st to end	Night	11% 7% 3 7% 5% 3 4 4 6% 5% 43%	2470
December	1st to 10th	Night	14% 10% 5% 9% 7% 4 6% 6% 4 6% 29%	2470
	11th to 20th	Night	14% 9% 5% 10% 7% 3 5% 4 5% 5% 32%	3042
	21st to end	Night	13% 12% 7% 12% 7% 4 6% 5% 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	40% 8% 10% 19% 18% 5%	2080
	11th to 20th	Day	49% 7% 12% 16% 13% 4	2090
	21st to end	Day	48% 8% 11% 20% 10% 2	2299
April	1st to 10th	Day	40% 8% 11% 22% 15% 3	2002
	11th to 20th	Day	42% 8% 11% 17% 18% 4	2153
	21st to end	Day	45% 9% 12% 21% 11% 2	2340
May	1st to 10th	Day	46% 11% 13% 18% 10% 1	2340
	11th to 20th	Day	54% 10% 13% 17% 6% 2	2305
	21st to end	Day	45% 13% 14% 21% 6% 1	2531
June	1st to 10th	Day	48% 12% 14% 17% 9% 1	2340
	11th to 20th	Day	46% 13% 14% 14% 11% 1	2340
	21st to end	Day	45% 13% 13% 17% 11% 1	2340
July	1st to 10th	Day	49% 13% 16% 14% 8% 1	2275
	11th to 20th	Day	51% 14% 15% 10% 9% 1	2271
	21st to end	Day	52% 13% 14% 15% 5% 1	2405
August	1st to 10th	Day	54% 13% 13% 14% 5%	2314
	11th to 20th	Day	55% 12% 12% 13% 7%	2303
	21st to end	Day	47% 11% 15% 17% 8% 3	2454
September	1st to 10th	Day	46% 9% 13% 17% 12% 3	1980
	11th to 20th	Day	49% 8% 11% 17% 14% 1	1980
	21st to end	Day	47% 8% 13% 15% 13% 4	1980
October	1st to 10th	Day	41% 6% 10% 20% 18% 5%	1900
	11th to 20th	Day	36% 7% 12% 21% 19% 5%	1800
	21st to end	Day	37% 7% 9% 22% 18% 7%	1980
November	1st to 10th	Day	33% 7% 9% 19% 27% 7%	1807
	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	42% 9% 10% 16% 18% 5%	2100
	11th to 20th	Night	46% 10% 12% 20% 10% 2	2090
	21st to end	Night	45% 10% 12% 19% 12% 2	2299
April	1st to 10th	Night	39% 10% 13% 21% 14% 3	2003
	11th to 20th	Night	37% 9% 13% 19% 17% 5%	1769
	21st to end	Night	40% 9% 13% 23% 13% 1	1620
May	1st to 10th	Night	42% 11% 15% 22% 8% 1	1620
	11th to 20th	Night	45% 13% 14% 20% 7% 1	1593
	21st to end	Night	41% 15% 17% 19% 7% 1	1745
June	1st to 10th	Night	39% 14% 17% 19% 10% 1	1620
	11th to 20th	Night	33% 15% 22% 22% 9% 1	1620
	21st to end	Night	36% 14% 18% 19% 10% 3	1620
July	1st to 10th	Night	38% 14% 17% 18% 11% 2	1575
	11th to 20th	Night	36% 16% 22% 16% 7% 2	1566
	21st to end	Night	36% 16% 21% 20% 6% 1	1672
August	1st to 10th	Night	42% 14% 18% 18% 8%	1600
	11th to 20th	Night	43% 15% 16% 16% 9% 1	1598
	21st to end	Night	39% 10% 19% 20% 10% 1	1879
September	1st to 10th	Night	41% 10% 15% 18% 13% 3	1980
	11th to 20th	Night	43% 9% 14% 18% 16% 1	1980
	21st to end	Night	44% 7% 12% 20% 15% 2	1980
October	1st to 10th	Night	39% 7% 11% 20% 19% 3	2059
	11th to 20th	Night	38% 7% 10% 23% 18% 4	2160
	21st to end	Night	35% 7% 9% 21% 20% 8%	2376
November	1st to 10th	Night	36% 6% 11% 18% 22% 7%	2268
	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	26% 26% 26% 14% 7% 1	428
	11th to 20th	Day	27% 22% 22% 17% 10% 2	412
	21st to end	Day	24% 21% 27% 14% 9% 4	420
May	1st to 10th	Day	22% 22% 33% 11% 7% 5%	423
	11th to 20th	Day	21% 15% 28% 20% 11% 6%	447
	21st to end	Day	16% 11% 22% 25% 14% 12%	485
June	1st to 10th	Day	15% 10% 28% 25% 15% 7%	450
	11th to 20th	Day	9% 10% 26% 28% 19% 8%	450
	21st to end	Day	10% 12% 33% 25% 12% 8%	450
July	1st to 10th	Day	9% 7% 21% 29% 21% 13%	445
	11th to 20th	Day	8% 7% 18% 34% 23% 10%	444
	21st to end	Day	11% 4 24% 27% 21% 13%	488
August	1st to 10th	Day	15% 7% 22% 26% 16% 14%	446
	11th to 20th	Day	9% 7% 21% 27% 25% 11%	439
	21st to end	Day	13% 4 20% 26% 20% 16%	495
September	1st to 10th	Day	12% 5% 18% 29% 25% 11%	450
	11th to 20th	Day	14% 7% 17% 26% 26% 10%	450
	21st to end	Day	22% 12% 21% 25% 16% 5%	450
October	1st to 10th	Day	22% 13% 20% 21% 21% 4	450
	11th to 20th	Day	16% 21% 26% 19% 15% 3	450
	21st to end	Day	19% 22% 25% 23% 8% 4	495
November	1st to 10th	Day	19% 18% 29% 21% 11% 2	405
	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	22% 22% 25% 24% 7%	729
	11th to 20th	Night	20% 20% 24% 23% 12% 1	674
	21st to end	Night	15% 19% 22% 32% 11% 1	540
May	1st to 10th	Night	17% 16% 29% 23% 13% 1	540
	11th to 20th	Night	15% 9% 24% 31% 18% 3	531
	21st to end	Night	13% 8% 17% 30% 26% 7%	584
June	1st to 10th	Night	9% 5% 20% 33% 28% 5%	540
	11th to 20th	Night	9% 5% 20% 26% 35% 5%	540
	21st to end	Night	7% 7% 19% 32% 31% 3	540
July	1st to 10th	Night	11% 2 14% 27% 41% 6%	525
	11th to 20th	Night	7% 4 11% 30% 41% 7%	522
	21st to end	Night	5% 4 12% 30% 39% 9%	591
August	1st to 10th	Night	11% 3 14% 28% 38% 6%	537
	11th to 20th	Night	13% 4 12% 29% 34% 7%	534
	21st to end	Night	11% 3 11% 30% 36% 8%	674
September	1st to 10th	Night	11% 7% 14% 29% 31% 8%	720
	11th to 20th	Night	18% 5% 14% 27% 31% 5%	720
	21st to end	Night	20% 9% 15% 27% 26% 2	720
October	1st to 10th	Night	16% 13% 18% 23% 24% 6%	720
	11th to 20th	Night	18% 17% 22% 27% 13% 2	720
	21st to end	Night	20% 17% 22% 27% 11% 3	792
November	1st to 10th	Night	17% 15% 22% 29% 14% 2	740
	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 2024-03-31 06:08:55. Version ac07

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