Goodnight Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goodnight Ridge clear sky chart from 2005-11-06 to 2025-07-21.

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	15% 8% 3 7% 4 4 5% 4 5% 7% 37%	120505
	Night	16% 9% 3 7% 4 4 4 3 5% 6% 39%	118539
Transparency	Day	45% 5% 10% 23% 15% 2	124213
	Night	45% 4 9% 22% 16% 3	122968
Seeing	Day	18% 9% 24% 24% 17% 8%	16153
	Night	18% 8% 25% 30% 17% 2	25684

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	15% 16% 8% 8% 4 4 4 3 5% 6% 28%	3724
	11th to 20th	Day	14% 13% 6% 14% 4 4 4 2 4 4 32%	4060
	21st to end	Day	21% 11% 6% 6% 5% 4 4 3 4 5% 31%	4466
February	1st to 10th	Day	18% 12% 4 9% 4 3 3 3 4 6% 32%	1995
	11th to 20th	Day	19% 10% 4 8% 5% 4 4 3 4 5% 33%	1948
	21st to end	Day	18% 12% 4 7% 5% 4 5% 3 6% 4 32%	1650
March	1st to 10th	Day	20% 12% 3 7% 3 4 4 3 3 5% 36%	4480
	11th to 20th	Day	14% 8% 2 6% 5% 3 3 3 5% 8% 43%	4950
	21st to end	Day	15% 9% 3 7% 4 4 4 3 5% 7% 37%	5478
April	1st to 10th	Day	16% 8% 3 6% 4 3 5% 4 6% 7% 39%	2400
	11th to 20th	Day	17% 8% 2 5% 4 4 4 3 5% 6% 40%	2374
	21st to end	Day	17% 8% 2 6% 5% 5% 4 4 6% 6% 37%	2590
May	1st to 10th	Day	21% 8% 3 8% 6% 5% 5% 5% 7% 8% 26%	5862
	11th to 20th	Day	18% 8% 3 8% 4 4 5% 4 6% 7% 33%	5861
	21st to end	Day	14% 6% 2 7% 5% 5% 6% 5% 7% 9% 32%	6433
June	1st to 10th	Day	12% 5% 2 6% 4 5% 5% 4 7% 6% 42%	2600
	11th to 20th	Day	8% 5% 2 5% 6% 6% 6% 4 7% 9% 41%	2750
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 7% 10% 42%	2800
July	1st to 10th	Day	12% 6% 2 7% 5% 6% 4 4 7% 9% 38%	4580
	11th to 20th	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 10% 43%	4362
	21st to end	Day	14% 10% 4 9% 7% 6% 6% 5% 7% 7% 25%	4466
August	1st to 10th	Day	8% 4 2 5% 4 4 5% 4 7% 11% 47%	4104
	11th to 20th	Day	9% 5% 2 6% 4 5% 6% 5% 7% 10% 38%	3898
	21st to end	Day	5% 3 2 5% 4 4 5% 4 6% 9% 53%	4180
September	1st to 10th	Day	14% 6% 2 6% 5% 4 5% 4 5% 7% 44%	2185
	11th to 20th	Day	12% 6% 2 5% 3 3 4 4 6% 8% 47%	2090
	21st to end	Day	15% 6% 2 5% 5% 3 4 3 5% 6% 46%	2090
October	1st to 10th	Day	11% 4 2 5% 3 3 4 4 5% 6% 55%	2090
	11th to 20th	Day	13% 6% 2 6% 4 3 3 3 4 6% 50%	1981
	21st to end	Day	20% 6% 2 5% 3 3 3 4 4 5% 45%	1927
November	1st to 10th	Day	13% 6% 1 5% 3 3 3 2 4 6% 54%	1762
	11th to 20th	Day	16% 9% 3 5% 4 4 3 2 4 6% 43%	1800
	21st to end	Day	18% 10% 3 6% 3 3 5% 4 4 6% 38%	1800
December	1st to 10th	Day	19% 11% 3 7% 4 3 4 3 4 4 39%	2930
	11th to 20th	Day	20% 13% 4 9% 6% 4 4 3 4 5% 29%	3373
	21st to end	Day	23% 16% 5% 8% 4 4 4 3 4 5% 23%	4466
January	1st to 10th	Night	16% 17% 5% 13% 5% 4 4 3 4 5% 25%	6106
	11th to 20th	Night	17% 15% 6% 10% 6% 4 4 2 3 4 29%	5900
	21st to end	Night	21% 11% 3 6% 4 4 3 3 3 6% 37%	6490
February	1st to 10th	Night	22% 11% 5% 8% 4 4 4 4 5% 6% 27%	2400
	11th to 20th	Night	21% 10% 4 9% 4 3 4 2 4 5% 33%	2338
	21st to end	Night	21% 12% 3 8% 4 4 3 3 4 5% 31%	1980
March	1st to 10th	Night	21% 14% 2 6% 4 4 3 3 4 5% 35%	5373
	11th to 20th	Night	14% 7% 2 6% 4 4 4 3 5% 5% 46%	5008
	21st to end	Night	16% 9% 3 8% 6% 5% 4 4 5% 6% 35%	5467
April	1st to 10th	Night	16% 7% 2 5% 5% 4 4 4 5% 7% 41%	2015
	11th to 20th	Night	16% 7% 3 7% 4 4 4 3 5% 6% 42%	1975
	21st to end	Night	16% 8% 3 7% 5% 5% 4 4 5% 7% 38%	1808
May	1st to 10th	Night	22% 9% 3 8% 5% 5% 5% 4 5% 8% 26%	4033
	11th to 20th	Night	17% 7% 3 7% 5% 5% 6% 4 7% 7% 32%	4032
	21st to end	Night	12% 7% 3 7% 5% 5% 5% 5% 7% 9% 36%	4421
June	1st to 10th	Night	10% 5% 2 5% 4 4 3 4 6% 10% 48%	1800
	11th to 20th	Night	7% 5% 2 5% 4 3 4 4 7% 10% 49%	1643
	21st to end	Night	6% 4 2 4 4 5% 6% 4 7% 12% 47%	1600
July	1st to 10th	Night	8% 5% 2 6% 5% 5% 5% 4 6% 9% 46%	2610
	11th to 20th	Night	7% 4 2 5% 3 4 4 3 7% 10% 50%	2815
	21st to end	Night	13% 8% 4 9% 6% 5% 6% 5% 7% 8% 30%	3087
August	1st to 10th	Night	7% 5% 2 5% 3 4 4 3 6% 9% 52%	2825
	11th to 20th	Night	8% 5% 2 6% 4 5% 6% 4 6% 9% 45%	2927
	21st to end	Night	3 3 1 3 3 2 3 3 5% 9% 63%	3476
September	1st to 10th	Night	12% 4 2 5% 4 4 4 3 4 7% 50%	1976
	11th to 20th	Night	11% 5% 2 5% 4 4 3 4 5% 7% 51%	2090
	21st to end	Night	12% 5% 2 5% 3 4 3 2 5% 6% 52%	2090
October	1st to 10th	Night	9% 4 1 5% 3 3 3 3 4 6% 59%	2090
	11th to 20th	Night	15% 5% 3 4 4 3 4 3 4 6% 49%	2197
	21st to end	Night	17% 7% 2 5% 4 3 4 3 4 6% 46%	2669
November	1st to 10th	Night	13% 6% 2 5% 4 3 4 3 5% 5% 49%	2536
	11th to 20th	Night	15% 9% 3 5% 4 3 3 3 4 6% 44%	2600
	21st to end	Night	18% 10% 3 5% 4 3 4 3 4 6% 39%	2600
December	1st to 10th	Night	20% 11% 4 7% 4 3 3 2 3 4 38%	4250
	11th to 20th	Night	22% 11% 4 7% 3 3 3 2 5% 5% 34%	4822
	21st to end	Night	23% 15% 5% 9% 6% 5% 5% 3 4 5% 21%	6490

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	57% 4 8% 21% 9% 1	3725
	11th to 20th	Day	57% 3 6% 18% 14% 3	4060
	21st to end	Day	55% 3 8% 20% 11% 3	4466
February	1st to 10th	Day	55% 3 8% 21% 11% 2	1995
	11th to 20th	Day	54% 4 8% 20% 11% 3	1958
	21st to end	Day	53% 4 8% 20% 11% 4	1650
March	1st to 10th	Day	52% 3 5% 17% 17% 6%	4480
	11th to 20th	Day	41% 4 9% 25% 19% 2	4950
	21st to end	Day	46% 4 10% 27% 12% 1	5478
April	1st to 10th	Day	43% 6% 12% 23% 15% 2	2400
	11th to 20th	Day	45% 4 9% 22% 17% 3	2374
	21st to end	Day	47% 6% 9% 24% 12% 2	2590
May	1st to 10th	Day	54% 6% 11% 18% 10%	5897
	11th to 20th	Day	51% 5% 12% 21% 11%	5865
	21st to end	Day	45% 6% 14% 18% 15% 1	6447
June	1st to 10th	Day	40% 7% 9% 24% 17% 2	2600
	11th to 20th	Day	37% 8% 13% 23% 17% 2	2750
	21st to end	Day	35% 7% 14% 21% 18% 4	2800
July	1st to 10th	Day	42% 6% 13% 22% 16% 1	4511
	11th to 20th	Day	35% 7% 11% 32% 13% 2	4289
	21st to end	Day	56% 6% 11% 16% 9% 1	4324
August	1st to 10th	Day	31% 5% 13% 37% 13% 1	4091
	11th to 20th	Day	39% 5% 11% 27% 15% 2	3937
	21st to end	Day	27% 6% 11% 36% 17% 3	4179
September	1st to 10th	Day	39% 6% 11% 20% 18% 5%	2185
	11th to 20th	Day	35% 6% 10% 23% 23% 3	2090
	21st to end	Day	39% 4 8% 23% 23% 3	2090
October	1st to 10th	Day	21% 3 5% 27% 41% 3	3480
	11th to 20th	Day	26% 3 9% 27% 32% 3	3273
	21st to end	Day	31% 3 7% 29% 21% 8%	3151
November	1st to 10th	Day	34% 3 8% 28% 23% 4	1762
	11th to 20th	Day	43% 3 8% 22% 19% 5%	1800
	21st to end	Day	47% 4 8% 21% 19% 2	1800
December	1st to 10th	Day	50% 2 7% 24% 16% 1	2930
	11th to 20th	Day	59% 3 8% 17% 11% 1	3370
	21st to end	Day	64% 4 11% 15% 6% 1	4466
January	1st to 10th	Night	62% 4 8% 17% 9% 1	6106
	11th to 20th	Night	60% 3 5% 17% 11% 3	5900
	21st to end	Night	51% 3 8% 22% 15% 2	6490
February	1st to 10th	Night	57% 4 10% 17% 10% 1	2400
	11th to 20th	Night	55% 3 7% 20% 13% 2	2339
	21st to end	Night	56% 4 9% 15% 13% 3	1980
March	1st to 10th	Night	53% 3 5% 21% 13% 4	5373
	11th to 20th	Night	39% 4 9% 25% 20% 3	5008
	21st to end	Night	50% 4 9% 23% 13% 1	5467
April	1st to 10th	Night	41% 7% 11% 21% 17% 3	2015
	11th to 20th	Night	44% 4 8% 20% 18% 6%	1975
	21st to end	Night	46% 6% 10% 22% 14% 2	1808
May	1st to 10th	Night	54% 7% 10% 19% 8% 1	4060
	11th to 20th	Night	49% 8% 12% 22% 9% 1	4033
	21st to end	Night	41% 8% 16% 22% 13% 2	4429
June	1st to 10th	Night	32% 6% 14% 26% 18% 4	1800
	11th to 20th	Night	30% 7% 14% 24% 21% 4	1643
	21st to end	Night	30% 8% 17% 22% 17% 6%	1600
July	1st to 10th	Night	35% 7% 12% 26% 18% 3	2570
	11th to 20th	Night	29% 5% 13% 34% 16% 2	2765
	21st to end	Night	51% 7% 12% 18% 10% 1	2988
August	1st to 10th	Night	29% 5% 14% 35% 15% 1	2814
	11th to 20th	Night	36% 6% 11% 30% 16% 1	2954
	21st to end	Night	19% 5% 14% 36% 22% 4	3476
September	1st to 10th	Night	33% 7% 11% 22% 21% 6%	1976
	11th to 20th	Night	32% 6% 11% 23% 25% 3	2090
	21st to end	Night	34% 6% 7% 25% 24% 5%	2090
October	1st to 10th	Night	21% 3 7% 21% 46% 3	3480
	11th to 20th	Night	26% 3 7% 25% 35% 6%	3644
	21st to end	Night	31% 2 8% 21% 30% 8%	4395
November	1st to 10th	Night	36% 4 9% 24% 23% 4	2536
	11th to 20th	Night	42% 4 7% 21% 21% 6%	2600
	21st to end	Night	48% 3 8% 23% 16% 2	2600
December	1st to 10th	Night	52% 3 8% 22% 15%	4250
	11th to 20th	Night	53% 3 10% 20% 13% 1	4824
	21st to end	Night	66% 4 9% 15% 6%	6490

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	26% 19% 30% 17% 7% 1	300
	11th to 20th	Day	32% 21% 30% 14% 4	300
	21st to end	Day	25% 20% 37% 15% 3	330
February	1st to 10th	Day	27% 17% 39% 13% 4	300
	11th to 20th	Day	34% 23% 31% 10% 3	300
	21st to end	Day	30% 18% 37% 13% 2	249
March	1st to 10th	Day	28% 16% 37% 15% 3 1	300
	11th to 20th	Day	23% 17% 38% 16% 6% 1	483
	21st to end	Day	30% 14% 31% 19% 5% 1	550
April	1st to 10th	Day	22% 16% 27% 23% 10% 1	500
	11th to 20th	Day	22% 13% 28% 23% 11% 3	492
	21st to end	Day	21% 11% 31% 24% 9% 4	500
May	1st to 10th	Day	21% 14% 27% 21% 12% 5%	503
	11th to 20th	Day	20% 7% 25% 25% 16% 7%	527
	21st to end	Day	14% 7% 22% 27% 18% 12%	573
June	1st to 10th	Day	13% 4 19% 26% 25% 12%	530
	11th to 20th	Day	9% 3 20% 33% 24% 12%	680
	21st to end	Day	11% 4 21% 29% 23% 12%	730
July	1st to 10th	Day	13% 3 15% 24% 24% 20%	721
	11th to 20th	Day	10% 3 17% 28% 27% 14%	593
	21st to end	Day	13% 2 13% 28% 30% 15%	532
August	1st to 10th	Day	11% 3 13% 26% 28% 18%	486
	11th to 20th	Day	13% 3 14% 29% 29% 12%	479
	21st to end	Day	10% 1 9% 28% 29% 22%	539
September	1st to 10th	Day	13% 3 14% 27% 29% 14%	490
	11th to 20th	Day	12% 2 14% 25% 32% 16%	490
	21st to end	Day	18% 6% 17% 25% 23% 10%	490
October	1st to 10th	Day	12% 3 18% 33% 26% 8%	490
	11th to 20th	Day	15% 13% 27% 28% 14% 4	490
	21st to end	Day	20% 11% 34% 22% 13%	376
November	1st to 10th	Day	20% 6% 32% 26% 12% 4	300
	11th to 20th	Day	25% 13% 30% 24% 7% 1	300
	21st to end	Day	27% 8% 32% 24% 8% 1	300
December	1st to 10th	Day	24% 19% 27% 23% 6% 1	300
	11th to 20th	Day	24% 12% 37% 17% 9%	300
	21st to end	Day	30% 19% 31% 16% 4	330
January	1st to 10th	Night	24% 15% 32% 26% 4	901
	11th to 20th	Night	29% 14% 33% 21% 4	800
	21st to end	Night	24% 14% 36% 25% 1	880
February	1st to 10th	Night	28% 13% 33% 25% 2	800
	11th to 20th	Night	29% 13% 36% 20% 2	783
	21st to end	Night	27% 13% 38% 19% 2	660
March	1st to 10th	Night	23% 15% 32% 25% 6%	800
	11th to 20th	Night	24% 10% 36% 24% 6%	800
	21st to end	Night	23% 11% 29% 29% 7%	880
April	1st to 10th	Night	18% 11% 32% 31% 7%	615
	11th to 20th	Night	19% 10% 30% 30% 11% 1	593
	21st to end	Night	19% 8% 33% 29% 10% 2	600
May	1st to 10th	Night	21% 6% 27% 30% 15% 2	600
	11th to 20th	Night	17% 5% 20% 35% 20% 4	591
	21st to end	Night	9% 3 19% 36% 28% 5%	650
June	1st to 10th	Night	10% 2 19% 40% 27% 3	600
	11th to 20th	Night	8% 2 15% 42% 29% 4	600
	21st to end	Night	6% 3 16% 42% 31% 3	600
July	1st to 10th	Night	11% 1 10% 30% 38% 10%	585
	11th to 20th	Night	6% 3 11% 33% 40% 7%	582
	21st to end	Night	11% 3 9% 35% 37% 6%	624
August	1st to 10th	Night	9% 1 9% 33% 42% 6%	567
	11th to 20th	Night	8% 1 10% 40% 34% 7%	564
	21st to end	Night	6% 7% 33% 48% 5%	627
September	1st to 10th	Night	13% 1 11% 33% 37% 5%	646
	11th to 20th	Night	12% 3 13% 30% 36% 6%	760
	21st to end	Night	13% 4 19% 32% 29% 3	760
October	1st to 10th	Night	11% 4 18% 33% 29% 6%	760
	11th to 20th	Night	19% 5% 24% 33% 17% 1	760
	21st to end	Night	19% 6% 30% 31% 13% 1	836
November	1st to 10th	Night	15% 8% 26% 33% 16% 2	780
	11th to 20th	Night	19% 9% 32% 29% 11%	800
	21st to end	Night	24% 11% 24% 30% 11% 1	800
December	1st to 10th	Night	27% 11% 28% 28% 6%	800
	11th to 20th	Night	25% 11% 33% 23% 7% 1	800
	21st to end	Night	29% 11% 30% 25% 4	880

Page generated at 2025-07-18 01:09:58. Version ac07

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