Coyote Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coyote Ridge clear sky chart from 2005-11-06 to 2025-11-18.

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 9% 6% 5% 5% 4 6% 7% 31%	126760
	Night	13% 9% 4 9% 6% 5% 5% 4 6% 7% 33%	123601
Transparency	Day	48% 8% 12% 20% 10% 2	130360
	Night	48% 8% 12% 20% 11% 2	128071
Seeing	Day	22% 18% 27% 19% 10% 4	16150
	Night	19% 17% 27% 25% 11% 1	25728

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	12% 12% 7% 16% 9% 5% 5% 3 5% 6% 21%	3889
	11th to 20th	Day	10% 14% 7% 17% 11% 9% 7% 4 4 4 15%	4060
	21st to end	Day	14% 11% 7% 14% 8% 5% 5% 4 5% 5% 22%	4466
February	1st to 10th	Day	13% 15% 6% 10% 8% 5% 4 3 5% 6% 25%	1800
	11th to 20th	Day	14% 12% 5% 12% 7% 5% 5% 4 6% 6% 24%	1753
	21st to end	Day	15% 12% 4 12% 6% 5% 5% 3 5% 6% 28%	1654
March	1st to 10th	Day	15% 9% 7% 8% 5% 5% 4 3 5% 6% 33%	4935
	11th to 20th	Day	11% 7% 4 9% 5% 4 4 4 7% 8% 36%	4980
	21st to end	Day	12% 9% 4 9% 6% 5% 5% 4 6% 6% 35%	5465
April	1st to 10th	Day	14% 13% 4 9% 5% 5% 5% 4 6% 7% 29%	2360
	11th to 20th	Day	13% 12% 4 7% 5% 5% 4 4 5% 6% 36%	2374
	21st to end	Day	19% 9% 3 6% 4 4 5% 4 5% 6% 33%	2526
May	1st to 10th	Day	20% 9% 3 8% 6% 6% 5% 5% 6% 7% 25%	5862
	11th to 20th	Day	22% 9% 2 7% 4 4 5% 4 7% 8% 28%	5942
	21st to end	Day	16% 6% 3 8% 5% 6% 6% 5% 7% 8% 30%	6934
June	1st to 10th	Day	13% 7% 2 7% 5% 6% 5% 4 7% 9% 35%	2800
	11th to 20th	Day	13% 7% 3 8% 5% 6% 5% 5% 8% 10% 32%	2800
	21st to end	Day	11% 6% 2 6% 5% 5% 6% 5% 8% 10% 37%	2800
July	1st to 10th	Day	6% 4 3 8% 6% 6% 6% 5% 7% 8% 42%	6360
	11th to 20th	Day	7% 6% 3 8% 7% 7% 8% 6% 8% 11% 30%	5930
	21st to end	Day	8% 7% 3 8% 5% 5% 5% 5% 7% 9% 37%	6424
August	1st to 10th	Day	15% 6% 2 8% 5% 6% 6% 5% 7% 9% 29%	4234
	11th to 20th	Day	9% 6% 3 8% 6% 6% 7% 6% 7% 8% 34%	4174
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 5% 7% 9% 41%	4326
September	1st to 10th	Day	15% 7% 2 5% 4 5% 4 4 6% 7% 42%	2400
	11th to 20th	Day	12% 6% 3 6% 4 4 5% 3 5% 7% 45%	2302
	21st to end	Day	20% 9% 3 7% 5% 5% 4 3 5% 6% 32%	2141
October	1st to 10th	Day	14% 7% 2 6% 4 5% 5% 4 6% 7% 40%	2000
	11th to 20th	Day	16% 10% 2 6% 5% 4 5% 3 5% 5% 37%	2000
	21st to end	Day	16% 9% 3 7% 5% 5% 4 4 5% 6% 36%	2200
November	1st to 10th	Day	9% 9% 3 8% 4 4 5% 3 6% 5% 44%	2042
	11th to 20th	Day	11% 10% 4 8% 6% 4 5% 5% 7% 8% 31%	1677
	21st to end	Day	14% 14% 4 9% 7% 5% 4 4 6% 5% 27%	1600
December	1st to 10th	Day	12% 9% 5% 17% 7% 6% 5% 4 6% 9% 20%	2600
	11th to 20th	Day	20% 12% 7% 12% 4 5% 3 3 3 5% 26%	2990
	21st to end	Day	17% 13% 6% 15% 8% 5% 5% 4 5% 5% 17%	3960
January	1st to 10th	Night	9% 10% 6% 17% 12% 7% 5% 4 5% 6% 18%	6055
	11th to 20th	Night	9% 11% 6% 15% 10% 8% 5% 4 5% 7% 20%	5900
	21st to end	Night	15% 9% 4 11% 9% 6% 4 3 4 6% 29%	6490
February	1st to 10th	Night	12% 11% 5% 10% 5% 5% 5% 4 6% 6% 30%	2600
	11th to 20th	Night	14% 10% 3 11% 7% 6% 5% 6% 6% 7% 25%	2533
	21st to end	Night	14% 10% 5% 10% 8% 5% 5% 4 7% 7% 27%	1973
March	1st to 10th	Night	15% 10% 4 8% 5% 5% 5% 4 6% 6% 32%	4918
	11th to 20th	Night	9% 6% 5% 8% 4 4 4 3 5% 6% 45%	4980
	21st to end	Night	9% 9% 3 8% 5% 5% 4 3 6% 7% 40%	5467
April	1st to 10th	Night	15% 12% 4 8% 6% 4 4 3 6% 6% 32%	2038
	11th to 20th	Night	12% 9% 3 7% 6% 4 4 5% 6% 8% 37%	1975
	21st to end	Night	16% 6% 3 7% 6% 4 4 4 6% 7% 40%	1890
May	1st to 10th	Night	23% 10% 3 8% 5% 4 5% 4 5% 7% 25%	4033
	11th to 20th	Night	25% 9% 2 5% 4 4 4 3 5% 8% 31%	3946
	21st to end	Night	16% 8% 3 8% 5% 5% 5% 5% 6% 9% 31%	3920
June	1st to 10th	Night	11% 6% 3 6% 5% 5% 4 4 6% 8% 44%	1600
	11th to 20th	Night	11% 6% 2 7% 5% 4 5% 5% 7% 8% 40%	1600
	21st to end	Night	10% 4 2 4 5% 4 6% 5% 7% 10% 44%	1600
July	1st to 10th	Night	6% 6% 3 7% 6% 5% 6% 4 7% 9% 41%	3598
	11th to 20th	Night	6% 7% 3 9% 6% 6% 6% 5% 7% 9% 36%	4009
	21st to end	Night	7% 6% 2 7% 5% 5% 6% 5% 6% 8% 42%	4427
August	1st to 10th	Night	15% 5% 2 6% 4 5% 5% 5% 7% 10% 36%	2915
	11th to 20th	Night	10% 6% 2 7% 5% 6% 5% 4 6% 7% 43%	2875
	21st to end	Night	11% 7% 2 5% 3 4 4 4 6% 9% 46%	3538
September	1st to 10th	Night	13% 6% 2 5% 4 4 4 3 5% 6% 48%	2000
	11th to 20th	Night	11% 6% 2 5% 3 3 4 3 5% 8% 50%	2095
	21st to end	Night	19% 8% 3 6% 4 4 4 3 5% 7% 37%	2257
October	1st to 10th	Night	15% 7% 2 5% 3 4 3 4 5% 7% 44%	2400
	11th to 20th	Night	14% 7% 2 5% 5% 5% 5% 4 5% 7% 42%	2400
	21st to end	Night	16% 7% 2 6% 4 5% 4 4 6% 7% 40%	2640
November	1st to 10th	Night	9% 8% 3 7% 6% 4 4 3 5% 6% 45%	2473
	11th to 20th	Night	13% 10% 4 8% 6% 5% 4 5% 6% 6% 34%	2875
	21st to end	Night	13% 10% 4 9% 6% 6% 6% 5% 6% 6% 30%	2800
December	1st to 10th	Night	11% 8% 4 15% 6% 5% 5% 4 6% 11% 24%	4580
	11th to 20th	Night	17% 10% 5% 12% 5% 5% 5% 4 5% 6% 25%	5205
	21st to end	Night	15% 13% 7% 14% 8% 5% 6% 4 5% 5% 17%	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	62% 7% 12% 13% 4 1	3890
	11th to 20th	Day	72% 5% 9% 8% 5% 2	4060
	21st to end	Day	62% 8% 10% 11% 9% 1	4466
February	1st to 10th	Day	60% 7% 12% 14% 7% 1	1800
	11th to 20th	Day	60% 7% 10% 15% 8%	1762
	21st to end	Day	58% 6% 12% 14% 8% 2	1654
March	1st to 10th	Day	50% 6% 12% 21% 9% 3	4935
	11th to 20th	Day	42% 10% 13% 26% 8% 3	4980
	21st to end	Day	47% 7% 13% 18% 13% 2	5465
April	1st to 10th	Day	53% 8% 11% 15% 11% 2	2360
	11th to 20th	Day	49% 7% 11% 16% 15% 2	2374
	21st to end	Day	50% 7% 10% 22% 9% 1	2526
May	1st to 10th	Day	55% 8% 11% 17% 7% 2	5897
	11th to 20th	Day	51% 7% 11% 23% 7% 1	5946
	21st to end	Day	47% 10% 14% 18% 9% 2	6949
June	1st to 10th	Day	43% 10% 12% 23% 11% 1	2800
	11th to 20th	Day	45% 10% 13% 20% 11% 1	2800
	21st to end	Day	40% 10% 14% 24% 12% 1	2800
July	1st to 10th	Day	38% 9% 12% 27% 13% 2	6290
	11th to 20th	Day	42% 12% 16% 21% 9%	5860
	21st to end	Day	40% 7% 10% 24% 17% 1	6240
August	1st to 10th	Day	48% 9% 15% 20% 8%	4221
	11th to 20th	Day	43% 8% 12% 27% 10%	4213
	21st to end	Day	37% 8% 14% 27% 13% 1	4326
September	1st to 10th	Day	42% 7% 11% 20% 17% 4	2400
	11th to 20th	Day	38% 6% 11% 28% 16% 2	2302
	21st to end	Day	52% 6% 12% 16% 12% 1	2141
October	1st to 10th	Day	35% 6% 9% 27% 19% 4	3260
	11th to 20th	Day	41% 5% 12% 22% 12% 9%	3240
	21st to end	Day	33% 5% 12% 28% 21% 1	3538
November	1st to 10th	Day	41% 7% 12% 20% 16% 5%	2042
	11th to 20th	Day	50% 8% 11% 16% 12% 3	1677
	21st to end	Day	58% 7% 11% 15% 8%	1600
December	1st to 10th	Day	61% 6% 19% 11% 3 1	2600
	11th to 20th	Day	62% 5% 11% 16% 6%	2986
	21st to end	Day	65% 8% 11% 11% 5%	3960
January	1st to 10th	Night	64% 7% 10% 10% 7% 1	6055
	11th to 20th	Night	61% 8% 13% 13% 5% 2	5900
	21st to end	Night	58% 7% 11% 16% 7% 1	6490
February	1st to 10th	Night	54% 8% 11% 18% 9% 1	2600
	11th to 20th	Night	57% 8% 9% 16% 9%	2535
	21st to end	Night	55% 8% 10% 15% 9% 2	1973
March	1st to 10th	Night	50% 6% 13% 21% 8% 2	4918
	11th to 20th	Night	38% 8% 15% 27% 8% 4	4980
	21st to end	Night	43% 6% 15% 19% 15% 2	5467
April	1st to 10th	Night	53% 6% 11% 16% 13% 1	2038
	11th to 20th	Night	44% 8% 13% 18% 14% 3	1975
	21st to end	Night	43% 8% 11% 26% 9% 3	1890
May	1st to 10th	Night	57% 8% 11% 14% 8% 3	4060
	11th to 20th	Night	50% 8% 11% 23% 7% 1	3947
	21st to end	Night	47% 10% 13% 20% 7% 2	3927
June	1st to 10th	Night	38% 8% 12% 27% 14% 1	1600
	11th to 20th	Night	40% 9% 14% 26% 10% 2	1600
	21st to end	Night	34% 10% 17% 23% 14% 1	1600
July	1st to 10th	Night	38% 10% 13% 25% 12% 2	3560
	11th to 20th	Night	41% 11% 18% 20% 10% 1	3960
	21st to end	Night	36% 9% 13% 23% 18% 1	4297
August	1st to 10th	Night	42% 11% 17% 21% 8%	2904
	11th to 20th	Night	39% 7% 11% 28% 13% 1	2902
	21st to end	Night	35% 7% 13% 30% 13% 2	3538
September	1st to 10th	Night	36% 8% 13% 23% 17% 3	2000
	11th to 20th	Night	33% 6% 12% 29% 19% 1	2095
	21st to end	Night	46% 7% 11% 20% 14% 1	2257
October	1st to 10th	Night	35% 6% 10% 26% 22% 1	3920
	11th to 20th	Night	32% 6% 13% 22% 18% 9%	3899
	21st to end	Night	33% 5% 11% 28% 19% 4	4252
November	1st to 10th	Night	40% 6% 10% 20% 19% 4	2473
	11th to 20th	Night	49% 8% 9% 19% 12% 3	2875
	21st to end	Night	53% 8% 11% 18% 9% 1	2800
December	1st to 10th	Night	54% 9% 19% 14% 4 1	4580
	11th to 20th	Night	59% 6% 13% 16% 5%	5208
	21st to end	Night	66% 8% 10% 10% 5%	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	33% 32% 21% 10% 4 1	263
	11th to 20th	Day	39% 26% 27% 6% 1	300
	21st to end	Day	32% 27% 30% 10% 2	330
February	1st to 10th	Day	33% 27% 29% 10% 1	300
	11th to 20th	Day	42% 25% 27% 6% 1	300
	21st to end	Day	35% 28% 26% 10% 1	354
March	1st to 10th	Day	31% 23% 28% 15% 2	500
	11th to 20th	Day	30% 28% 25% 13% 4 1	500
	21st to end	Day	28% 25% 31% 12% 3 1	550
April	1st to 10th	Day	31% 23% 26% 16% 4 1	500
	11th to 20th	Day	24% 22% 29% 15% 8% 3	492
	21st to end	Day	28% 19% 30% 15% 6% 1	500
May	1st to 10th	Day	27% 21% 24% 18% 7% 3	503
	11th to 20th	Day	25% 18% 28% 16% 9% 3	527
	21st to end	Day	19% 12% 26% 23% 13% 6%	573
June	1st to 10th	Day	18% 14% 29% 22% 13% 4	530
	11th to 20th	Day	19% 13% 27% 24% 13% 5%	530
	21st to end	Day	12% 15% 29% 26% 15% 3	530
July	1st to 10th	Day	10% 10% 27% 24% 19% 10%	525
	11th to 20th	Day	10% 9% 27% 31% 16% 8%	524
	21st to end	Day	13% 9% 27% 28% 16% 7%	576
August	1st to 10th	Day	11% 10% 25% 28% 19% 8%	526
	11th to 20th	Day	15% 8% 24% 26% 17% 11%	519
	21st to end	Day	12% 8% 24% 27% 20% 9%	583
September	1st to 10th	Day	19% 11% 18% 23% 19% 10%	530
	11th to 20th	Day	12% 5% 23% 29% 21% 9%	530
	21st to end	Day	26% 13% 24% 20% 13% 4	530
October	1st to 10th	Day	18% 12% 25% 23% 18% 4	530
	11th to 20th	Day	24% 18% 29% 19% 9% 1	530
	21st to end	Day	24% 21% 30% 18% 6% 1	583
November	1st to 10th	Day	20% 22% 29% 18% 9% 2	527
	11th to 20th	Day	26% 25% 29% 16% 3	235
	21st to end	Day	32% 24% 30% 13% 2 1	200
December	1st to 10th	Day	31% 33% 24% 8% 4 1	200
	11th to 20th	Day	33% 29% 25% 12% 2	200
	21st to end	Day	30% 25% 27% 14% 4	220
January	1st to 10th	Night	22% 32% 32% 12% 3	800
	11th to 20th	Night	28% 23% 31% 16% 2	800
	21st to end	Night	23% 28% 33% 14% 1	880
February	1st to 10th	Night	24% 25% 30% 19% 2	800
	11th to 20th	Night	25% 32% 31% 11% 1	783
	21st to end	Night	25% 22% 37% 14% 2	660
March	1st to 10th	Night	24% 24% 32% 19% 2	800
	11th to 20th	Night	26% 25% 25% 16% 6% 1	800
	21st to end	Night	22% 22% 35% 16% 5% 1	880
April	1st to 10th	Night	22% 24% 30% 19% 4	800
	11th to 20th	Night	18% 20% 28% 25% 8% 1	791
	21st to end	Night	20% 16% 28% 29% 7%	690
May	1st to 10th	Night	23% 14% 22% 30% 10% 1	600
	11th to 20th	Night	23% 9% 27% 31% 9% 1	557
	21st to end	Night	13% 8% 22% 33% 21% 2	433
June	1st to 10th	Night	11% 8% 26% 35% 19% 1	400
	11th to 20th	Night	12% 6% 28% 36% 18% 1	400
	21st to end	Night	11% 6% 29% 36% 17% 1	400
July	1st to 10th	Night	11% 4 20% 40% 22% 2	390
	11th to 20th	Night	6% 6% 19% 37% 28% 4	562
	21st to end	Night	8% 6% 19% 41% 25% 2	657
August	1st to 10th	Night	9% 3 17% 41% 27% 3	597
	11th to 20th	Night	9% 6% 16% 38% 26% 5%	594
	21st to end	Night	12% 5% 19% 35% 25% 4	845
September	1st to 10th	Night	15% 7% 18% 34% 23% 4	800
	11th to 20th	Night	12% 5% 17% 36% 27% 4	800
	21st to end	Night	22% 10% 21% 28% 17% 3	800
October	1st to 10th	Night	17% 9% 24% 30% 19% 2	800
	11th to 20th	Night	18% 17% 29% 25% 9% 1	800
	21st to end	Night	22% 20% 27% 25% 6% 1	880
November	1st to 10th	Night	16% 15% 30% 28% 9% 1	820
	11th to 20th	Night	23% 22% 27% 21% 6% 1	829
	21st to end	Night	23% 23% 31% 18% 6% 1	800
December	1st to 10th	Night	25% 26% 28% 18% 3	800
	11th to 20th	Night	25% 27% 27% 19% 3	800
	21st to end	Night	22% 25% 32% 20% 2	880

Page generated at 2025-11-15 00:55:54. Version ac07

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