AllSky Camera - 108 Mile Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the AllSky Camera - 108 Mile Ranch clear sky chart from 2005-11-06 to 2025-05-11.

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	8% 10% 4 9% 6% 6% 6% 5% 6% 8% 33%	116734
	Night	8% 12% 5% 11% 7% 6% 6% 5% 7% 7% 28%	120894
Transparency	Day	48% 5% 14% 21% 9% 2	116481
	Night	54% 6% 14% 18% 7% 1	120793
Seeing	Day	15% 14% 25% 26% 16% 5%	16513
	Night	16% 12% 25% 29% 16% 2	24844

By Month

Percentage Cloud Cover NW (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	6% 18% 7% 19% 9% 7% 6% 4 6% 6% 13%	3179
	11th to 20th	Day	6% 11% 4 9% 7% 6% 6% 6% 10% 8% 27%	3159
	21st to end	Day	6% 13% 5% 11% 7% 5% 6% 5% 6% 8% 27%	3844
February	1st to 10th	Day	8% 19% 6% 13% 7% 5% 4 4 5% 5% 23%	1660
	11th to 20th	Day	7% 14% 5% 11% 7% 6% 6% 4 7% 7% 27%	1755
	21st to end	Day	5% 14% 5% 13% 8% 5% 6% 4 6% 7% 25%	1531
March	1st to 10th	Day	3 12% 5% 11% 8% 7% 7% 5% 7% 8% 26%	4518
	11th to 20th	Day	2 9% 4 11% 7% 7% 7% 5% 8% 10% 28%	4929
	21st to end	Day	6% 12% 4 11% 8% 7% 6% 5% 6% 8% 26%	5785
April	1st to 10th	Day	6% 14% 6% 11% 8% 6% 7% 5% 7% 8% 23%	2400
	11th to 20th	Day	8% 14% 5% 12% 7% 6% 6% 4 6% 7% 25%	2444
	21st to end	Day	8% 11% 4 10% 7% 8% 6% 5% 7% 7% 28%	2790
May	1st to 10th	Day	7% 10% 3 9% 6% 5% 5% 4 6% 9% 35%	4560
	11th to 20th	Day	7% 10% 4 10% 7% 6% 6% 5% 8% 9% 29%	4380
	21st to end	Day	14% 13% 4 11% 7% 6% 6% 5% 6% 7% 22%	5117
June	1st to 10th	Day	16% 11% 4 9% 6% 5% 6% 4 6% 6% 26%	3040
	11th to 20th	Day	14% 10% 4 10% 7% 6% 6% 5% 7% 8% 23%	3040
	21st to end	Day	10% 8% 3 8% 6% 6% 6% 5% 6% 7% 33%	3040
July	1st to 10th	Day	5% 5% 1 4 3 4 4 4 5% 6% 58%	4904
	11th to 20th	Day	4 4 1 4 3 3 4 3 5% 7% 62%	4740
	21st to end	Day	7% 6% 2 5% 4 4 4 4 7% 9% 48%	4959
August	1st to 10th	Day	5% 4 2 5% 4 3 4 4 6% 9% 55%	4401
	11th to 20th	Day	4 3 2 5% 4 5% 6% 5% 8% 11% 45%	4252
	21st to end	Day	9% 6% 2 7% 5% 5% 5% 4 7% 10% 41%	4381
September	1st to 10th	Day	9% 6% 2 6% 4 3 4 3 6% 7% 49%	2280
	11th to 20th	Day	12% 7% 3 7% 5% 6% 4 4 5% 8% 41%	2280
	21st to end	Day	13% 9% 3 8% 5% 5% 5% 5% 6% 7% 34%	2023
October	1st to 10th	Day	13% 11% 3 10% 5% 5% 5% 4 6% 7% 31%	3180
	11th to 20th	Day	15% 10% 4 9% 5% 4 4 4 5% 8% 33%	3114
	21st to end	Day	9% 12% 5% 9% 6% 6% 6% 5% 7% 6% 28%	3044
November	1st to 10th	Day	11% 16% 5% 12% 6% 5% 6% 5% 5% 6% 22%	1568
	11th to 20th	Day	11% 12% 4 11% 7% 6% 6% 5% 6% 8% 23%	1600
	21st to end	Day	8% 19% 5% 12% 8% 7% 7% 5% 7% 7% 17%	1460
December	1st to 10th	Day	7% 13% 4 12% 8% 9% 8% 6% 7% 7% 19%	2100
	11th to 20th	Day	5% 13% 5% 15% 8% 9% 8% 6% 8% 8% 15%	2262
	21st to end	Day	6% 17% 5% 12% 8% 6% 6% 4 6% 7% 21%	3015
January	1st to 10th	Night	8% 19% 7% 16% 8% 6% 6% 4 6% 6% 13%	6784
	11th to 20th	Night	5% 12% 5% 12% 7% 7% 7% 6% 8% 7% 25%	6739
	21st to end	Night	6% 14% 6% 12% 6% 6% 6% 4 7% 7% 25%	7110
February	1st to 10th	Night	8% 18% 7% 13% 7% 6% 5% 3 5% 6% 22%	2736
	11th to 20th	Night	7% 14% 4 11% 7% 6% 5% 4 6% 6% 30%	2532
	21st to end	Night	5% 14% 6% 11% 7% 6% 6% 4 6% 7% 27%	2098
March	1st to 10th	Night	3 14% 6% 10% 6% 6% 6% 6% 8% 10% 25%	5376
	11th to 20th	Night	2 10% 4 11% 7% 6% 7% 7% 9% 10% 28%	5056
	21st to end	Night	6% 13% 5% 11% 7% 7% 7% 5% 6% 7% 25%	5189
April	1st to 10th	Night	6% 12% 5% 11% 8% 7% 6% 5% 6% 7% 27%	2000
	11th to 20th	Night	6% 13% 4 10% 7% 5% 6% 5% 7% 8% 30%	1902
	21st to end	Night	7% 10% 4 10% 7% 6% 7% 4 6% 8% 31%	1610
May	1st to 10th	Night	7% 12% 4 10% 7% 5% 5% 4 6% 6% 35%	2620
	11th to 20th	Night	11% 11% 4 11% 7% 6% 5% 5% 5% 7% 29%	2519
	21st to end	Night	17% 15% 4 10% 6% 5% 5% 4 7% 6% 20%	2454
June	1st to 10th	Night	15% 10% 3 8% 7% 5% 6% 4 7% 8% 26%	1140
	11th to 20th	Night	16% 11% 4 9% 8% 5% 6% 5% 7% 7% 21%	1140
	21st to end	Night	10% 9% 3 9% 8% 7% 6% 4 6% 6% 32%	1140
July	1st to 10th	Night	7% 5% 2 5% 5% 4 5% 4 5% 7% 51%	2052
	11th to 20th	Night	4 4 2 5% 5% 4 4 5% 7% 7% 54%	2220
	21st to end	Night	8% 7% 3 7% 5% 5% 6% 5% 6% 7% 40%	2593
August	1st to 10th	Night	5% 4 2 8% 5% 5% 6% 4 5% 7% 50%	2529
	11th to 20th	Night	6% 6% 3 6% 5% 6% 6% 4 8% 10% 40%	2561
	21st to end	Night	9% 8% 3 9% 5% 5% 5% 4 8% 8% 37%	3291
September	1st to 10th	Night	9% 5% 2 6% 5% 5% 4 4 7% 7% 47%	1900
	11th to 20th	Night	9% 6% 2 6% 4 5% 5% 4 7% 8% 42%	1900
	21st to end	Night	12% 9% 3 7% 4 4 5% 5% 6% 7% 38%	2153
October	1st to 10th	Night	14% 10% 4 10% 5% 6% 5% 4 5% 6% 30%	3800
	11th to 20th	Night	10% 10% 3 8% 6% 6% 6% 5% 8% 9% 30%	3821
	21st to end	Night	10% 11% 4 9% 7% 6% 6% 4 6% 7% 29%	4509
November	1st to 10th	Night	13% 14% 4 11% 7% 6% 6% 5% 7% 7% 21%	2730
	11th to 20th	Night	9% 14% 5% 11% 8% 6% 5% 5% 6% 7% 24%	2800
	21st to end	Night	8% 18% 5% 11% 8% 7% 5% 4 6% 7% 20%	2918
December	1st to 10th	Night	7% 12% 4 11% 7% 9% 8% 5% 7% 8% 21%	5078
	11th to 20th	Night	7% 20% 8% 14% 8% 7% 6% 5% 6% 6% 14%	5930
	21st to end	Night	6% 14% 6% 13% 8% 7% 6% 4 6% 7% 23%	7964

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	70% 6% 12% 11% 2	3179
	11th to 20th	Day	49% 7% 20% 12% 6% 5%	3180
	21st to end	Day	53% 6% 20% 18% 2	3844
February	1st to 10th	Day	64% 3 11% 12% 10% 1	1660
	11th to 20th	Day	55% 5% 15% 16% 8%	1764
	21st to end	Day	57% 6% 14% 17% 7%	1531
March	1st to 10th	Day	54% 6% 10% 21% 9%	4518
	11th to 20th	Day	48% 3 14% 24% 11%	4929
	21st to end	Day	55% 5% 11% 20% 9%	5785
April	1st to 10th	Day	57% 7% 11% 18% 7%	2400
	11th to 20th	Day	57% 5% 10% 17% 10% 1	2444
	21st to end	Day	53% 5% 11% 20% 10% 1	2790
May	1st to 10th	Day	45% 4 11% 27% 13% 1	4560
	11th to 20th	Day	50% 4 11% 26% 8%	4383
	21st to end	Day	61% 4 11% 18% 6%	5118
June	1st to 10th	Day	56% 6% 9% 15% 11% 3	3040
	11th to 20th	Day	58% 6% 13% 17% 6%	3040
	21st to end	Day	48% 5% 16% 20% 10% 2	3040
July	1st to 10th	Day	26% 4 10% 25% 23% 11%	4829
	11th to 20th	Day	22% 4 11% 31% 25% 7%	4659
	21st to end	Day	31% 5% 17% 27% 14% 6%	4802
August	1st to 10th	Day	27% 4 12% 36% 21% 1	4384
	11th to 20th	Day	30% 8% 22% 30% 9% 1	4294
	21st to end	Day	38% 6% 27% 22% 5% 1	4380
September	1st to 10th	Day	35% 4 20% 28% 10% 3	2280
	11th to 20th	Day	43% 4 13% 27% 10% 2	2280
	21st to end	Day	49% 5% 15% 19% 10% 1	2023
October	1st to 10th	Day	51% 4 21% 18% 5%	3180
	11th to 20th	Day	50% 3 18% 25% 4	3114
	21st to end	Day	54% 7% 19% 18% 3	3044
November	1st to 10th	Day	60% 6% 13% 15% 6%	1568
	11th to 20th	Day	59% 6% 15% 16% 4	1600
	21st to end	Day	64% 6% 13% 12% 5%	1460
December	1st to 10th	Day	62% 8% 19% 10% 1	2100
	11th to 20th	Day	64% 7% 17% 8% 4	2264
	21st to end	Day	62% 5% 15% 14% 4	3015
January	1st to 10th	Night	71% 4 11% 11% 3	6784
	11th to 20th	Night	54% 7% 15% 14% 6% 4	6780
	21st to end	Night	56% 6% 19% 16% 2	7110
February	1st to 10th	Night	64% 4 10% 14% 8% 1	2736
	11th to 20th	Night	55% 5% 13% 18% 7% 1	2534
	21st to end	Night	54% 5% 15% 18% 7% 1	2098
March	1st to 10th	Night	51% 6% 10% 20% 12%	5376
	11th to 20th	Night	46% 3 15% 25% 11%	5057
	21st to end	Night	56% 5% 13% 16% 10%	5189
April	1st to 10th	Night	53% 7% 14% 20% 6% 1	2000
	11th to 20th	Night	51% 5% 10% 22% 11%	1902
	21st to end	Night	51% 5% 10% 22% 11% 1	1610
May	1st to 10th	Night	48% 4 10% 24% 12% 2	2620
	11th to 20th	Night	54% 4 9% 25% 8%	2519
	21st to end	Night	62% 4 13% 16% 4	2454
June	1st to 10th	Night	53% 7% 8% 20% 9% 3	1140
	11th to 20th	Night	60% 6% 13% 14% 6%	1140
	21st to end	Night	52% 5% 13% 20% 8% 2	1140
July	1st to 10th	Night	33% 5% 8% 20% 25% 9%	2018
	11th to 20th	Night	27% 5% 9% 30% 25% 4	2178
	21st to end	Night	41% 5% 13% 22% 11% 8%	2511
August	1st to 10th	Night	33% 4 10% 34% 19% 1	2521
	11th to 20th	Night	37% 6% 20% 26% 9% 1	2585
	21st to end	Night	43% 5% 26% 20% 6% 1	3291
September	1st to 10th	Night	34% 6% 15% 30% 13% 2	1900
	11th to 20th	Night	37% 5% 16% 26% 12% 3	1900
	21st to end	Night	44% 6% 16% 21% 11% 1	2153
October	1st to 10th	Night	54% 3 19% 19% 5%	3800
	11th to 20th	Night	48% 6% 17% 24% 5%	3821
	21st to end	Night	53% 7% 18% 18% 4	4509
November	1st to 10th	Night	60% 7% 14% 14% 5%	2730
	11th to 20th	Night	58% 7% 15% 13% 7% 1	2800
	21st to end	Night	63% 5% 14% 11% 6%	2918
December	1st to 10th	Night	58% 8% 20% 11% 3	5078
	11th to 20th	Night	69% 7% 12% 9% 3	5927
	21st to end	Night	61% 5% 16% 15% 4	7964

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	17% 19% 36% 18% 8% 4	200
	11th to 20th	Day	12% 24% 31% 21% 12% 1	200
	21st to end	Day	21% 15% 30% 23% 10% 1	220
February	1st to 10th	Day	20% 19% 32% 18% 8% 4	260
	11th to 20th	Day	14% 14% 32% 28% 11% 1	395
	21st to end	Day	12% 21% 32% 21% 11% 3	355
March	1st to 10th	Day	16% 21% 27% 22% 13% 2	500
	11th to 20th	Day	14% 22% 28% 21% 12% 4	500
	21st to end	Day	17% 21% 26% 20% 12% 3	550
April	1st to 10th	Day	17% 21% 27% 24% 9% 2	500
	11th to 20th	Day	16% 24% 22% 21% 11% 6%	492
	21st to end	Day	14% 15% 29% 25% 13% 4	500
May	1st to 10th	Day	14% 17% 29% 24% 13% 3	503
	11th to 20th	Day	15% 11% 24% 27% 19% 5%	489
	21st to end	Day	18% 11% 21% 29% 16% 4	703
June	1st to 10th	Day	19% 13% 29% 24% 12% 3	870
	11th to 20th	Day	19% 11% 23% 29% 15% 3	870
	21st to end	Day	13% 9% 24% 28% 21% 6%	870
July	1st to 10th	Day	11% 7% 25% 29% 21% 6%	769
	11th to 20th	Day	9% 9% 22% 33% 21% 5%	668
	21st to end	Day	8% 6% 20% 35% 23% 7%	635
August	1st to 10th	Day	7% 5% 15% 35% 26% 11%	487
	11th to 20th	Day	7% 8% 21% 30% 22% 11%	477
	21st to end	Day	12% 7% 24% 27% 22% 8%	539
September	1st to 10th	Day	11% 12% 25% 29% 16% 8%	490
	11th to 20th	Day	14% 10% 18% 28% 22% 7%	490
	21st to end	Day	21% 12% 28% 23% 13% 3	490
October	1st to 10th	Day	22% 12% 22% 21% 17% 6%	490
	11th to 20th	Day	21% 19% 24% 19% 13% 4	468
	21st to end	Day	22% 17% 27% 21% 12% 2	313
November	1st to 10th	Day	23% 22% 32% 15% 7% 3	200
	11th to 20th	Day	24% 17% 22% 23% 13% 3	200
	21st to end	Day	17% 19% 28% 21% 11% 5%	200
December	1st to 10th	Day	13% 12% 26% 32% 14% 5%	200
	11th to 20th	Day	13% 19% 30% 23% 13% 4	200
	21st to end	Day	16% 18% 32% 21% 11% 2	220
January	1st to 10th	Night	22% 14% 31% 23% 9% 1	905
	11th to 20th	Night	18% 13% 28% 29% 11% 1	900
	21st to end	Night	15% 15% 29% 28% 11% 2	913
February	1st to 10th	Night	18% 16% 29% 23% 12% 2	800
	11th to 20th	Night	14% 11% 29% 36% 9% 1	784
	21st to end	Night	13% 12% 28% 30% 14% 2	660
March	1st to 10th	Night	15% 15% 26% 28% 14% 2	800
	11th to 20th	Night	11% 16% 32% 27% 12% 2	800
	21st to end	Night	13% 17% 22% 26% 19% 3	880
April	1st to 10th	Night	13% 12% 26% 29% 17% 3	800
	11th to 20th	Night	12% 11% 29% 30% 17% 2	714
	21st to end	Night	11% 13% 30% 28% 15% 2	410
May	1st to 10th	Night	13% 13% 24% 32% 17% 2	400
	11th to 20th	Night	15% 9% 23% 33% 17% 3	375
	21st to end	Night	18% 8% 23% 27% 22% 2	411
June	1st to 10th	Night	18% 10% 27% 29% 15% 1	380
	11th to 20th	Night	20% 8% 24% 29% 17% 2	380
	21st to end	Night	13% 6% 22% 35% 20% 5%	380
July	1st to 10th	Night	13% 6% 19% 32% 27% 2	370
	11th to 20th	Night	9% 7% 21% 34% 26% 3	368
	21st to end	Night	9% 6% 18% 33% 30% 5%	416
August	1st to 10th	Night	6% 3 14% 35% 36% 7%	378
	11th to 20th	Night	8% 5% 11% 36% 34% 6%	414
	21st to end	Night	12% 7% 19% 31% 27% 5%	707
September	1st to 10th	Night	11% 6% 19% 36% 24% 3	760
	11th to 20th	Night	13% 5% 16% 30% 30% 6%	760
	21st to end	Night	18% 10% 24% 30% 14% 3	760
October	1st to 10th	Night	20% 11% 19% 29% 18% 3	760
	11th to 20th	Night	18% 12% 24% 28% 16% 2	760
	21st to end	Night	21% 13% 30% 23% 11% 2	836
November	1st to 10th	Night	25% 15% 24% 26% 8% 2	780
	11th to 20th	Night	21% 16% 29% 24% 10% 1	800
	21st to end	Night	20% 16% 27% 26% 9% 2	918
December	1st to 10th	Night	16% 14% 25% 29% 14% 2	1055
	11th to 20th	Night	19% 16% 29% 26% 9% 1	1100
	21st to end	Night	18% 16% 31% 25% 9% 1	1210

Page generated at 2025-05-08 06:33:58. Version ac07

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