Lincoln Ridge Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lincoln Ridge Park 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% 9% 3 7% 5% 4 4 4 5% 7% 36%	120418
	Night	15% 10% 3 8% 4 4 4 3 5% 7% 37%	118692
Transparency	Day	45% 6% 10% 23% 15% 2	124112
	Night	45% 5% 10% 22% 15% 2	123135
Seeing	Day	19% 12% 26% 23% 13% 6%	16241
	Night	19% 10% 25% 28% 15% 2	25877

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% 18% 8% 10% 4 4 3 3 4 5% 27%	3617
	11th to 20th	Day	14% 14% 5% 14% 5% 5% 4 3 3 4 29%	4031
	21st to end	Day	21% 12% 7% 8% 5% 5% 4 3 4 5% 26%	4466
February	1st to 10th	Day	18% 15% 5% 8% 4 4 3 3 4 6% 31%	1921
	11th to 20th	Day	18% 12% 5% 9% 5% 4 3 3 5% 5% 31%	1948
	21st to end	Day	18% 14% 4 7% 5% 3 3 3 4 5% 32%	1650
March	1st to 10th	Day	18% 14% 4 8% 4 4 4 2 4 5% 34%	4515
	11th to 20th	Day	13% 8% 3 6% 5% 4 4 4 6% 7% 40%	4980
	21st to end	Day	17% 10% 3 7% 4 4 4 3 5% 7% 35%	5465
April	1st to 10th	Day	16% 9% 3 8% 4 4 4 4 5% 7% 35%	2365
	11th to 20th	Day	16% 8% 3 6% 4 3 5% 4 4 7% 39%	2418
	21st to end	Day	17% 8% 3 7% 4 5% 4 3 6% 7% 35%	2600
May	1st to 10th	Day	20% 8% 3 8% 5% 5% 6% 4 6% 8% 27%	5862
	11th to 20th	Day	20% 9% 3 7% 5% 4 4 4 5% 8% 33%	5861
	21st to end	Day	13% 6% 3 8% 6% 6% 6% 5% 7% 10% 31%	6433
June	1st to 10th	Day	12% 6% 2 7% 5% 4 5% 4 6% 7% 41%	2600
	11th to 20th	Day	9% 5% 2 6% 6% 4 5% 5% 6% 9% 42%	2779
	21st to end	Day	8% 6% 3 6% 6% 5% 6% 5% 6% 9% 40%	2800
July	1st to 10th	Day	12% 6% 3 6% 5% 5% 5% 4 6% 10% 38%	4580
	11th to 20th	Day	7% 5% 2 5% 5% 4 4 4 7% 10% 46%	4392
	21st to end	Day	11% 7% 3 9% 6% 6% 6% 6% 7% 8% 30%	4466
August	1st to 10th	Day	9% 5% 2 6% 4 4 5% 4 8% 10% 44%	4104
	11th to 20th	Day	8% 5% 2 7% 4 5% 6% 5% 7% 10% 41%	4044
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 9% 54%	4182
September	1st to 10th	Day	14% 5% 1 5% 4 4 5% 3 5% 6% 47%	2166
	11th to 20th	Day	8% 5% 2 6% 4 4 4 4 6% 9% 48%	2090
	21st to end	Day	18% 4 2 5% 4 3 4 2 4 6% 47%	2090
October	1st to 10th	Day	12% 4 1 7% 5% 4 4 3 4 6% 50%	2090
	11th to 20th	Day	14% 6% 2 6% 5% 3 4 3 4 7% 46%	1938
	21st to end	Day	20% 8% 2 6% 3 3 4 3 4 6% 40%	1944
November	1st to 10th	Day	9% 7% 2 5% 4 3 4 2 5% 6% 52%	1762
	11th to 20th	Day	15% 10% 3 8% 4 4 4 3 5% 6% 37%	1800
	21st to end	Day	18% 10% 4 7% 4 4 4 3 4 6% 37%	1800
December	1st to 10th	Day	18% 10% 3 7% 4 4 3 2 3 5% 39%	2930
	11th to 20th	Day	18% 14% 5% 9% 5% 5% 4 4 4 5% 27%	3373
	21st to end	Day	22% 19% 4 10% 5% 4 4 3 4 5% 20%	4356
January	1st to 10th	Night	15% 16% 6% 14% 6% 5% 4 4 4 5% 20%	6348
	11th to 20th	Night	15% 16% 7% 14% 6% 4 5% 2 4 4 23%	5905
	21st to end	Night	20% 13% 4 7% 4 4 4 3 4 5% 32%	6490
February	1st to 10th	Night	20% 13% 5% 8% 5% 4 4 3 5% 5% 28%	2475
	11th to 20th	Night	19% 12% 4 9% 4 4 4 3 5% 6% 30%	2338
	21st to end	Night	20% 14% 4 7% 4 3 3 2 5% 5% 31%	1980
March	1st to 10th	Night	19% 14% 3 6% 4 4 3 3 4 5% 36%	5337
	11th to 20th	Night	12% 8% 2 6% 4 3 5% 4 5% 7% 44%	4980
	21st to end	Night	16% 9% 3 9% 5% 5% 5% 4 5% 5% 33%	5467
April	1st to 10th	Night	14% 10% 3 6% 4 4 5% 4 6% 7% 36%	2050
	11th to 20th	Night	14% 8% 2 6% 4 5% 3 3 7% 7% 41%	1931
	21st to end	Night	16% 7% 3 7% 4 4 4 3 6% 9% 36%	1800
May	1st to 10th	Night	21% 10% 3 8% 5% 4 5% 4 6% 7% 28%	4033
	11th to 20th	Night	17% 7% 2 7% 5% 5% 5% 5% 7% 9% 33%	4032
	21st to end	Night	13% 6% 2 7% 4 5% 5% 4 6% 9% 38%	4421
June	1st to 10th	Night	9% 5% 2 5% 4 4 4 4 6% 10% 48%	1800
	11th to 20th	Night	9% 5% 2 5% 4 4 4 4 6% 11% 46%	1613
	21st to end	Night	6% 4 2 5% 5% 4 5% 5% 8% 11% 47%	1600
July	1st to 10th	Night	9% 5% 2 6% 5% 5% 3 3 6% 8% 49%	2610
	11th to 20th	Night	6% 4 2 5% 4 4 4 4 7% 9% 51%	2787
	21st to end	Night	11% 7% 3 8% 5% 5% 5% 4 6% 9% 37%	3087
August	1st to 10th	Night	8% 5% 2 7% 4 4 4 4 6% 10% 47%	2825
	11th to 20th	Night	8% 6% 2 7% 4 4 4 4 6% 8% 46%	2785
	21st to end	Night	4 3 1 3 3 3 4 3 6% 10% 61%	3470
September	1st to 10th	Night	12% 5% 2 5% 3 3 4 3 5% 7% 52%	1995
	11th to 20th	Night	8% 4 2 5% 4 3 4 4 6% 7% 52%	2090
	21st to end	Night	14% 5% 2 4 4 3 4 3 4 6% 49%	2090
October	1st to 10th	Night	8% 4 1 6% 4 3 4 3 4 7% 55%	2090
	11th to 20th	Night	15% 6% 2 5% 4 4 4 3 5% 7% 46%	2241
	21st to end	Night	18% 8% 2 6% 4 3 4 3 5% 6% 41%	2650
November	1st to 10th	Night	13% 6% 3 5% 4 3 3 3 5% 6% 47%	2536
	11th to 20th	Night	16% 8% 2 7% 4 4 3 3 6% 6% 39%	2600
	21st to end	Night	19% 12% 3 7% 5% 4 4 3 4 6% 34%	2600
December	1st to 10th	Night	17% 11% 4 7% 4 4 4 3 4 5% 38%	4250
	11th to 20th	Night	19% 14% 6% 10% 5% 4 3 3 4 6% 28%	4822
	21st to end	Night	21% 18% 6% 11% 5% 4 4 3 4 5% 18%	6564

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	60% 3 10% 18% 9%	3618
	11th to 20th	Day	59% 3 7% 16% 12% 2	4031
	21st to end	Day	61% 4 8% 19% 6% 3	4466
February	1st to 10th	Day	56% 4 9% 20% 11% 2	1921
	11th to 20th	Day	55% 4 9% 20% 11% 1	1958
	21st to end	Day	54% 4 9% 21% 11% 2	1650
March	1st to 10th	Day	53% 4 6% 18% 14% 5%	4515
	11th to 20th	Day	42% 5% 9% 27% 15% 2	4980
	21st to end	Day	48% 5% 12% 21% 12% 2	5465
April	1st to 10th	Day	45% 6% 11% 22% 14% 2	2365
	11th to 20th	Day	45% 5% 9% 22% 16% 3	2418
	21st to end	Day	47% 6% 11% 23% 11% 2	2600
May	1st to 10th	Day	52% 8% 12% 17% 11% 1	5897
	11th to 20th	Day	49% 6% 11% 23% 11% 1	5865
	21st to end	Day	44% 9% 13% 21% 12% 1	6447
June	1st to 10th	Day	40% 7% 11% 24% 17% 2	2600
	11th to 20th	Day	37% 8% 12% 22% 18% 2	2779
	21st to end	Day	38% 9% 13% 21% 15% 4	2800
July	1st to 10th	Day	40% 7% 11% 21% 19% 2	4511
	11th to 20th	Day	30% 8% 12% 31% 18% 1	4318
	21st to end	Day	48% 9% 11% 17% 13% 2	4324
August	1st to 10th	Day	32% 8% 15% 33% 12% 1	4091
	11th to 20th	Day	34% 8% 11% 31% 15% 1	4083
	21st to end	Day	27% 6% 14% 29% 20% 3	4181
September	1st to 10th	Day	37% 6% 10% 21% 20% 6%	2166
	11th to 20th	Day	32% 7% 12% 24% 22% 3	2090
	21st to end	Day	38% 5% 9% 24% 21% 2	2090
October	1st to 10th	Day	23% 4 8% 31% 32% 2	3480
	11th to 20th	Day	30% 4 9% 29% 28% 2	3204
	21st to end	Day	35% 3 10% 26% 23% 3	3181
November	1st to 10th	Day	34% 5% 10% 28% 21% 3	1762
	11th to 20th	Day	48% 4 6% 22% 17% 3	1800
	21st to end	Day	49% 4 9% 22% 15% 1	1800
December	1st to 10th	Day	49% 3 10% 25% 13%	2930
	11th to 20th	Day	60% 4 8% 18% 9% 1	3370
	21st to end	Day	67% 5% 9% 13% 6% 1	4356
January	1st to 10th	Night	65% 5% 8% 14% 8%	6348
	11th to 20th	Night	65% 4 7% 12% 9% 3	5905
	21st to end	Night	56% 3 8% 22% 11% 1	6490
February	1st to 10th	Night	58% 4 11% 19% 7% 1	2475
	11th to 20th	Night	56% 3 9% 19% 11% 1	2339
	21st to end	Night	55% 4 10% 17% 11% 3	1980
March	1st to 10th	Night	51% 3 6% 26% 11% 3	5337
	11th to 20th	Night	38% 5% 11% 26% 18% 1	4980
	21st to end	Night	51% 5% 7% 24% 11% 1	5467
April	1st to 10th	Night	44% 6% 10% 24% 13% 2	2050
	11th to 20th	Night	42% 5% 10% 20% 18% 6%	1931
	21st to end	Night	44% 5% 12% 23% 13% 3	1800
May	1st to 10th	Night	53% 9% 9% 19% 8% 2	4060
	11th to 20th	Night	45% 8% 14% 23% 9% 1	4033
	21st to end	Night	39% 9% 15% 22% 12% 3	4429
June	1st to 10th	Night	31% 7% 13% 25% 20% 3	1800
	11th to 20th	Night	32% 7% 14% 23% 21% 4	1613
	21st to end	Night	29% 9% 17% 23% 18% 5%	1600
July	1st to 10th	Night	34% 8% 11% 24% 18% 6%	2570
	11th to 20th	Night	28% 7% 12% 31% 20% 2	2738
	21st to end	Night	42% 7% 13% 22% 12% 4	2988
August	1st to 10th	Night	31% 8% 14% 33% 12% 1	2814
	11th to 20th	Night	34% 8% 10% 30% 18% 1	2812
	21st to end	Night	19% 7% 15% 34% 22% 3	3470
September	1st to 10th	Night	32% 6% 10% 26% 20% 6%	1995
	11th to 20th	Night	28% 7% 12% 24% 26% 3	2090
	21st to end	Night	37% 5% 8% 22% 24% 3	2090
October	1st to 10th	Night	22% 4 7% 25% 40% 2	3480
	11th to 20th	Night	26% 4 9% 26% 33% 2	3714
	21st to end	Night	32% 4 8% 22% 29% 5%	4363
November	1st to 10th	Night	37% 4 10% 22% 23% 4	2536
	11th to 20th	Night	45% 4 9% 20% 19% 4	2600
	21st to end	Night	52% 4 9% 20% 13% 1	2600
December	1st to 10th	Night	49% 4 11% 23% 12%	4250
	11th to 20th	Night	57% 5% 11% 18% 9% 1	4824
	21st to end	Night	69% 4 9% 13% 4	6564

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% 24% 31% 14% 3 1	300
	11th to 20th	Day	31% 27% 29% 12% 1	300
	21st to end	Day	30% 23% 32% 13% 2	330
February	1st to 10th	Day	29% 24% 34% 11% 2	300
	11th to 20th	Day	34% 27% 28% 9% 1 1	300
	21st to end	Day	32% 19% 39% 8% 2	249
March	1st to 10th	Day	27% 27% 31% 14% 1	309
	11th to 20th	Day	28% 21% 30% 15% 5%	500
	21st to end	Day	33% 17% 30% 16% 5%	550
April	1st to 10th	Day	27% 17% 28% 18% 9% 1	500
	11th to 20th	Day	23% 21% 27% 18% 8% 3	492
	21st to end	Day	22% 19% 33% 16% 8% 2	500
May	1st to 10th	Day	24% 12% 36% 16% 8% 4	503
	11th to 20th	Day	22% 11% 27% 24% 10% 5%	527
	21st to end	Day	15% 10% 27% 24% 16% 8%	573
June	1st to 10th	Day	15% 8% 23% 29% 18% 7%	530
	11th to 20th	Day	11% 6% 23% 34% 19% 7%	709
	21st to end	Day	10% 6% 27% 29% 17% 10%	730
July	1st to 10th	Day	14% 4 17% 27% 22% 16%	721
	11th to 20th	Day	9% 5% 21% 29% 23% 11%	609
	21st to end	Day	12% 4 19% 33% 20% 14%	532
August	1st to 10th	Day	11% 3 18% 28% 25% 15%	486
	11th to 20th	Day	12% 3 20% 34% 20% 11%	479
	21st to end	Day	8% 4 16% 29% 30% 14%	539
September	1st to 10th	Day	13% 5% 15% 30% 26% 10%	490
	11th to 20th	Day	10% 3 18% 27% 28% 15%	490
	21st to end	Day	20% 9% 20% 21% 22% 8%	490
October	1st to 10th	Day	11% 8% 22% 33% 18% 8%	490
	11th to 20th	Day	18% 14% 29% 22% 13% 3	490
	21st to end	Day	23% 12% 36% 21% 7% 1	393
November	1st to 10th	Day	15% 15% 35% 23% 8% 3	300
	11th to 20th	Day	23% 20% 31% 20% 5% 1	300
	21st to end	Day	27% 16% 33% 19% 4	300
December	1st to 10th	Day	25% 23% 33% 14% 5%	300
	11th to 20th	Day	23% 20% 37% 14% 5%	300
	21st to end	Day	30% 21% 34% 10% 4 1	330
January	1st to 10th	Night	23% 19% 32% 21% 5%	1000
	11th to 20th	Night	29% 20% 31% 17% 3	805
	21st to end	Night	25% 17% 32% 23% 2	880
February	1st to 10th	Night	27% 14% 34% 22% 2	800
	11th to 20th	Night	28% 17% 33% 20% 2	783
	21st to end	Night	29% 15% 34% 21% 1	660
March	1st to 10th	Night	25% 15% 30% 26% 4	800
	11th to 20th	Night	24% 15% 33% 21% 7% 1	800
	21st to end	Night	23% 13% 31% 26% 7%	880
April	1st to 10th	Night	20% 14% 31% 27% 8%	650
	11th to 20th	Night	18% 13% 29% 28% 11% 1	593
	21st to end	Night	19% 9% 34% 28% 10% 1	600
May	1st to 10th	Night	21% 8% 30% 28% 12% 1	600
	11th to 20th	Night	18% 6% 21% 35% 18% 2	591
	21st to end	Night	10% 4 22% 36% 24% 4	650
June	1st to 10th	Night	10% 3 20% 41% 24% 2	600
	11th to 20th	Night	11% 5% 15% 41% 27% 3	600
	21st to end	Night	6% 3 21% 40% 27% 3	600
July	1st to 10th	Night	12% 2 13% 32% 30% 10%	585
	11th to 20th	Night	7% 3 13% 36% 38% 4	582
	21st to end	Night	12% 2 12% 37% 33% 4	624
August	1st to 10th	Night	9% 1 10% 37% 38% 5%	567
	11th to 20th	Night	8% 2 13% 39% 33% 5%	564
	21st to end	Night	6% 1 11% 34% 40% 8%	627
September	1st to 10th	Night	13% 2 14% 33% 33% 5%	665
	11th to 20th	Night	9% 3 16% 30% 37% 5%	760
	21st to end	Night	16% 5% 22% 31% 24% 3	760
October	1st to 10th	Night	10% 5% 22% 34% 24% 4	760
	11th to 20th	Night	18% 9% 24% 32% 15% 2	760
	21st to end	Night	21% 11% 30% 25% 12% 1	836
November	1st to 10th	Night	17% 10% 26% 28% 17% 2	780
	11th to 20th	Night	21% 15% 28% 25% 10% 1	800
	21st to end	Night	26% 12% 26% 28% 8% 1	800
December	1st to 10th	Night	27% 13% 33% 21% 6%	800
	11th to 20th	Night	25% 13% 31% 24% 6% 1	800
	21st to end	Night	29% 16% 30% 22% 3	915

Page generated at 2025-07-18 01:10:01. Version ac07

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