OAOG Moose Creek
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the OAOG Moose Creek clear sky chart from 2005-11-06 to 2025-10-19.

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	16% 10% 3 8% 5% 5% 5% 4 5% 7% 32%	126959
	Night	17% 12% 4 9% 5% 5% 4 3 5% 6% 30%	122752
Transparency	Day	51% 6% 12% 21% 9% 1	130411
	Night	54% 5% 11% 19% 10% 1	127387
Seeing	Day	21% 12% 29% 23% 11% 3	15741
	Night	22% 9% 29% 29% 10% 1	24729

By Month

Percentage Cloud Cover NE (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% 19% 6% 15% 5% 5% 4 3 4 4 21%	3597
	11th to 20th	Day	12% 15% 7% 13% 6% 5% 5% 3 5% 6% 21%	3570
	21st to end	Day	11% 18% 6% 12% 6% 5% 5% 4 5% 6% 20%	4051
February	1st to 10th	Day	15% 16% 4 11% 6% 4 4 3 6% 6% 25%	1800
	11th to 20th	Day	14% 13% 5% 12% 6% 5% 5% 3 5% 5% 28%	1798
	21st to end	Day	19% 13% 4 8% 5% 4 5% 3 6% 5% 26%	1650
March	1st to 10th	Day	18% 12% 5% 12% 6% 5% 4 4 4 6% 26%	4476
	11th to 20th	Day	12% 13% 4 9% 6% 5% 6% 4 5% 7% 30%	4880
	21st to end	Day	18% 10% 3 9% 5% 3 4 3 5% 5% 35%	5846
April	1st to 10th	Day	22% 12% 3 8% 4 3 4 2 4 6% 33%	2400
	11th to 20th	Day	21% 9% 4 7% 5% 4 3 2 5% 6% 35%	2374
	21st to end	Day	22% 10% 4 7% 4 5% 4 3 4 5% 31%	2524
May	1st to 10th	Day	24% 11% 4 8% 5% 4 4 4 5% 6% 24%	6346
	11th to 20th	Day	18% 9% 3 10% 6% 5% 4 3 5% 7% 30%	6318
	21st to end	Day	21% 8% 3 7% 4 4 5% 4 5% 6% 32%	6949
June	1st to 10th	Day	21% 9% 3 7% 6% 5% 4 4 5% 6% 30%	2800
	11th to 20th	Day	14% 7% 2 6% 5% 5% 5% 5% 7% 8% 37%	2800
	21st to end	Day	19% 8% 2 7% 5% 5% 4 4 6% 9% 31%	2800
July	1st to 10th	Day	12% 7% 3 8% 5% 6% 6% 5% 7% 9% 33%	6360
	11th to 20th	Day	10% 6% 3 6% 4 5% 5% 4 7% 9% 41%	6360
	21st to end	Day	10% 6% 2 5% 4 4 5% 4 7% 9% 45%	6926
August	1st to 10th	Day	14% 7% 3 8% 5% 5% 5% 4 6% 9% 35%	4563
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 6% 9% 39%	4059
	21st to end	Day	15% 6% 2 6% 4 5% 5% 4 6% 9% 38%	4312
September	1st to 10th	Day	13% 6% 2 5% 4 4 5% 4 6% 8% 43%	2400
	11th to 20th	Day	13% 5% 1 5% 4 4 4 3 5% 6% 50%	2370
	21st to end	Day	17% 7% 2 7% 3 4 4 3 5% 7% 40%	2183
October	1st to 10th	Day	19% 7% 2 6% 4 4 4 4 5% 6% 38%	2000
	11th to 20th	Day	18% 10% 3 8% 5% 4 5% 4 5% 6% 30%	1980
	21st to end	Day	24% 11% 3 8% 5% 5% 5% 4 4 5% 28%	1905
November	1st to 10th	Day	16% 9% 4 7% 4 6% 4 5% 6% 7% 32%	1761
	11th to 20th	Day	16% 13% 4 8% 4 5% 5% 4 6% 7% 29%	1655
	21st to end	Day	20% 14% 4 10% 6% 5% 6% 3 5% 7% 21%	1600
December	1st to 10th	Day	21% 20% 6% 10% 6% 4 5% 5% 5% 5% 14%	2600
	11th to 20th	Day	18% 15% 5% 10% 6% 5% 5% 4 4 5% 23%	2986
	21st to end	Day	22% 15% 4 11% 5% 4 5% 3 4 5% 21%	3960
January	1st to 10th	Night	15% 20% 8% 13% 6% 4 4 2 4 4 20%	6349
	11th to 20th	Night	11% 16% 7% 16% 8% 6% 5% 3 5% 5% 18%	6315
	21st to end	Night	14% 17% 7% 13% 6% 5% 4 3 5% 5% 21%	6904
February	1st to 10th	Night	15% 14% 5% 12% 7% 6% 5% 4 5% 5% 22%	2600
	11th to 20th	Night	14% 14% 4 12% 6% 5% 4 4 5% 5% 28%	2488
	21st to end	Night	15% 15% 5% 9% 7% 5% 4 2 4 5% 29%	1980
March	1st to 10th	Night	21% 14% 4 9% 5% 4 4 3 4 4 29%	5364
	11th to 20th	Night	14% 12% 4 8% 5% 5% 5% 4 5% 8% 30%	5076
	21st to end	Night	18% 12% 3 8% 4 4 4 3 5% 6% 33%	5085
April	1st to 10th	Night	22% 11% 3 7% 5% 4 4 3 5% 6% 31%	2000
	11th to 20th	Night	20% 10% 3 7% 5% 4 4 3 5% 5% 35%	1975
	21st to end	Night	21% 9% 3 7% 4 4 3 3 5% 6% 34%	1893
May	1st to 10th	Night	22% 10% 4 8% 6% 6% 5% 4 6% 7% 22%	3594
	11th to 20th	Night	17% 9% 3 7% 4 5% 5% 3 6% 6% 35%	3575
	21st to end	Night	16% 11% 3 8% 5% 5% 5% 5% 6% 6% 31%	3926
June	1st to 10th	Night	17% 7% 2 6% 6% 7% 6% 4 6% 9% 30%	1600
	11th to 20th	Night	15% 6% 3 7% 4 4 5% 3 6% 9% 39%	1600
	21st to end	Night	18% 8% 2 7% 4 5% 4 5% 7% 7% 34%	1600
July	1st to 10th	Night	13% 8% 3 8% 5% 5% 5% 5% 7% 9% 33%	3600
	11th to 20th	Night	12% 6% 2 7% 4 4 4 4 6% 8% 42%	3600
	21st to end	Night	9% 6% 2 6% 4 4 5% 4 6% 8% 44%	3926
August	1st to 10th	Night	14% 7% 2 8% 4 4 4 4 6% 7% 39%	2586
	11th to 20th	Night	15% 7% 2 7% 4 4 5% 3 5% 7% 41%	2952
	21st to end	Night	12% 7% 2 7% 5% 4 5% 4 6% 8% 40%	3586
September	1st to 10th	Night	11% 5% 2 6% 6% 5% 5% 4 5% 6% 44%	2000
	11th to 20th	Night	13% 5% 2 6% 3 3 2 3 5% 7% 50%	2030
	21st to end	Night	16% 6% 2 7% 5% 4 4 4 5% 6% 43%	2215
October	1st to 10th	Night	18% 8% 2 6% 5% 4 4 3 5% 7% 39%	2400
	11th to 20th	Night	19% 9% 3 7% 4 5% 5% 3 5% 6% 34%	2377
	21st to end	Night	22% 9% 3 8% 5% 5% 5% 3 4 6% 29%	2693
November	1st to 10th	Night	19% 11% 3 8% 5% 4 3 3 4 7% 33%	2537
	11th to 20th	Night	18% 10% 3 8% 6% 4 5% 3 5% 5% 32%	2742
	21st to end	Night	21% 13% 5% 10% 5% 5% 4 3 4 6% 24%	2800
December	1st to 10th	Night	19% 16% 6% 13% 7% 5% 5% 4 5% 5% 16%	4580
	11th to 20th	Night	24% 15% 5% 9% 5% 4 4 2 3 4 25%	5208
	21st to end	Night	25% 17% 4 11% 4 4 4 3 4 4 20%	6996

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	68% 4 10% 13% 4 1	3598
	11th to 20th	Day	64% 5% 11% 12% 8%	3600
	21st to end	Day	64% 6% 12% 11% 7% 1	4051
February	1st to 10th	Day	60% 6% 9% 19% 4 2	1800
	11th to 20th	Day	58% 4 13% 16% 7% 1	1807
	21st to end	Day	60% 4 12% 14% 9% 1	1650
March	1st to 10th	Day	60% 5% 9% 14% 10% 3	4479
	11th to 20th	Day	53% 5% 18% 14% 9% 1	4880
	21st to end	Day	51% 4 8% 19% 16% 2	5846
April	1st to 10th	Day	54% 3 8% 19% 13% 3	2400
	11th to 20th	Day	51% 4 7% 20% 16% 2	2374
	21st to end	Day	55% 5% 8% 16% 13% 3	2524
May	1st to 10th	Day	60% 5% 8% 17% 8% 2	6357
	11th to 20th	Day	53% 7% 12% 18% 9% 1	6322
	21st to end	Day	51% 7% 11% 20% 10% 1	6949
June	1st to 10th	Day	53% 6% 11% 17% 12% 1	2800
	11th to 20th	Day	42% 7% 12% 24% 12% 2	2800
	21st to end	Day	49% 7% 13% 21% 10% 1	2800
July	1st to 10th	Day	45% 7% 13% 26% 9%	6290
	11th to 20th	Day	38% 7% 13% 30% 12%	6285
	21st to end	Day	34% 6% 14% 37% 9%	6728
August	1st to 10th	Day	44% 7% 16% 24% 9%	4549
	11th to 20th	Day	41% 7% 16% 29% 7% 1	4098
	21st to end	Day	42% 7% 17% 23% 11%	4312
September	1st to 10th	Day	38% 7% 15% 29% 12%	2400
	11th to 20th	Day	35% 6% 12% 33% 14%	2370
	21st to end	Day	43% 7% 13% 26% 11%	2183
October	1st to 10th	Day	46% 5% 11% 28% 9%	3260
	11th to 20th	Day	47% 5% 15% 25% 7% 1	3220
	21st to end	Day	48% 5% 17% 23% 6%	3117
November	1st to 10th	Day	51% 6% 14% 21% 7% 1	1761
	11th to 20th	Day	54% 6% 12% 17% 11%	1655
	21st to end	Day	63% 7% 13% 12% 5%	1600
December	1st to 10th	Day	70% 7% 12% 10% 2	2600
	11th to 20th	Day	64% 6% 10% 15% 6%	2986
	21st to end	Day	66% 5% 8% 16% 5%	3960
January	1st to 10th	Night	69% 4 11% 12% 4	6349
	11th to 20th	Night	68% 6% 11% 10% 5%	6360
	21st to end	Night	65% 4 9% 10% 10% 1	6904
February	1st to 10th	Night	63% 5% 10% 15% 6% 1	2600
	11th to 20th	Night	59% 4 11% 18% 8%	2490
	21st to end	Night	58% 4 8% 18% 10% 1	1980
March	1st to 10th	Night	59% 4 6% 15% 12% 3	5374
	11th to 20th	Night	52% 5% 16% 16% 8% 3	5077
	21st to end	Night	53% 3 7% 22% 13% 2	5085
April	1st to 10th	Night	55% 4 9% 18% 13% 2	2000
	11th to 20th	Night	51% 5% 8% 19% 15% 2	1975
	21st to end	Night	51% 5% 9% 18% 15% 3	1893
May	1st to 10th	Night	59% 7% 8% 16% 7% 3	3600
	11th to 20th	Night	48% 7% 12% 18% 13% 1	3576
	21st to end	Night	50% 8% 10% 18% 13% 1	3927
June	1st to 10th	Night	49% 8% 13% 19% 12% 1	1600
	11th to 20th	Night	42% 5% 13% 22% 17% 2	1600
	21st to end	Night	46% 7% 14% 20% 13% 1	1600
July	1st to 10th	Night	45% 7% 16% 21% 11%	3560
	11th to 20th	Night	39% 6% 14% 30% 12%	3552
	21st to end	Night	36% 8% 12% 28% 16%	3809
August	1st to 10th	Night	42% 7% 16% 26% 9%	2576
	11th to 20th	Night	42% 6% 15% 28% 8%	2979
	21st to end	Night	40% 7% 15% 25% 12% 1	3586
September	1st to 10th	Night	40% 7% 10% 28% 15% 1	2000
	11th to 20th	Night	33% 6% 13% 34% 13% 1	2030
	21st to end	Night	42% 6% 12% 27% 13% 1	2215
October	1st to 10th	Night	43% 6% 13% 28% 10% 1	3920
	11th to 20th	Night	45% 5% 14% 26% 9%	3876
	21st to end	Night	48% 6% 17% 20% 10%	4431
November	1st to 10th	Night	52% 5% 14% 21% 8% 1	2537
	11th to 20th	Night	53% 5% 12% 18% 10% 1	2742
	21st to end	Night	62% 6% 12% 15% 5%	2800
December	1st to 10th	Night	70% 6% 11% 11% 2	4580
	11th to 20th	Night	65% 4 7% 14% 9% 1	5208
	21st to end	Night	67% 4 6% 13% 10%	6996

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% 14% 31% 22% 8%	200
	11th to 20th	Day	23% 18% 36% 18% 6% 1	200
	21st to end	Day	18% 15% 35% 25% 8%	240
February	1st to 10th	Day	30% 20% 35% 12% 4	300
	11th to 20th	Day	24% 19% 35% 20% 1	345
	21st to end	Day	28% 13% 34% 22% 2	414
March	1st to 10th	Day	24% 14% 33% 23% 6%	500
	11th to 20th	Day	20% 18% 35% 21% 4 1	500
	21st to end	Day	28% 13% 32% 17% 9% 1	550
April	1st to 10th	Day	28% 17% 28% 20% 7% 1	500
	11th to 20th	Day	27% 20% 25% 16% 10% 2	492
	21st to end	Day	28% 15% 30% 16% 9% 2	500
May	1st to 10th	Day	25% 11% 30% 23% 8% 3	503
	11th to 20th	Day	18% 12% 33% 22% 12% 3	527
	21st to end	Day	19% 12% 29% 25% 13% 2	573
June	1st to 10th	Day	25% 12% 26% 25% 9% 4	530
	11th to 20th	Day	15% 12% 29% 29% 12% 4	530
	21st to end	Day	23% 12% 28% 22% 12% 3	530
July	1st to 10th	Day	14% 9% 24% 31% 17% 5%	525
	11th to 20th	Day	11% 9% 29% 30% 18% 3	524
	21st to end	Day	13% 8% 27% 32% 17% 3	576
August	1st to 10th	Day	15% 6% 20% 35% 19% 5%	526
	11th to 20th	Day	14% 6% 20% 31% 20% 9%	519
	21st to end	Day	16% 7% 25% 28% 15% 8%	583
September	1st to 10th	Day	15% 8% 27% 22% 18% 10%	530
	11th to 20th	Day	11% 5% 23% 25% 23% 13%	530
	21st to end	Day	18% 11% 29% 18% 17% 6%	530
October	1st to 10th	Day	22% 12% 25% 20% 15% 6%	530
	11th to 20th	Day	23% 15% 32% 20% 8% 2	522
	21st to end	Day	31% 13% 25% 22% 8%	442
November	1st to 10th	Day	25% 16% 27% 21% 9% 1	395
	11th to 20th	Day	25% 15% 33% 19% 7%	255
	21st to end	Day	30% 18% 26% 21% 5% 2	200
December	1st to 10th	Day	30% 15% 27% 21% 7%	200
	11th to 20th	Day	28% 22% 31% 16% 3 1	200
	21st to end	Day	29% 21% 31% 13% 6% 1	220
January	1st to 10th	Night	26% 14% 32% 25% 4	800
	11th to 20th	Night	28% 12% 30% 24% 6% 1	800
	21st to end	Night	19% 8% 35% 31% 6%	880
February	1st to 10th	Night	21% 11% 38% 25% 4	800
	11th to 20th	Night	22% 12% 38% 23% 4	783
	21st to end	Night	23% 10% 35% 28% 3	660
March	1st to 10th	Night	26% 10% 32% 26% 7%	800
	11th to 20th	Night	22% 13% 34% 26% 4	800
	21st to end	Night	24% 10% 28% 29% 7%	880
April	1st to 10th	Night	29% 10% 29% 27% 5%	800
	11th to 20th	Night	23% 13% 33% 23% 8%	791
	21st to end	Night	27% 9% 29% 27% 8% 1	693
May	1st to 10th	Night	24% 9% 29% 28% 8% 3	400
	11th to 20th	Night	23% 7% 31% 29% 10% 1	394
	21st to end	Night	16% 3 35% 33% 12%	433
June	1st to 10th	Night	19% 4 29% 39% 9%	400
	11th to 20th	Night	17% 6% 29% 36% 12% 1	400
	21st to end	Night	18% 6% 28% 33% 15% 1	400
July	1st to 10th	Night	10% 6% 25% 41% 17%	390
	11th to 20th	Night	12% 3 24% 43% 17% 1	388
	21st to end	Night	12% 4 23% 47% 13% 1	438
August	1st to 10th	Night	14% 3 19% 45% 19% 1	398
	11th to 20th	Night	15% 4 17% 37% 25% 2	632
	21st to end	Night	14% 5% 23% 38% 18% 2	880
September	1st to 10th	Night	13% 7% 23% 39% 17% 1	800
	11th to 20th	Night	17% 5% 18% 34% 24% 3	800
	21st to end	Night	19% 6% 27% 27% 21% 2	800
October	1st to 10th	Night	24% 5% 26% 30% 14% 1	800
	11th to 20th	Night	24% 7% 30% 28% 10%	793
	21st to end	Night	28% 11% 28% 28% 6%	836
November	1st to 10th	Night	27% 11% 25% 27% 9% 1	780
	11th to 20th	Night	24% 12% 33% 22% 9% 1	800
	21st to end	Night	27% 12% 30% 24% 8%	800
December	1st to 10th	Night	30% 10% 33% 22% 5%	800
	11th to 20th	Night	29% 12% 32% 22% 5% 1	800
	21st to end	Night	33% 11% 31% 20% 5%	880

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