Stonelick Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stonelick Lake State Park clear sky chart from 2005-11-06 to 2025-07-06.

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	14% 9% 3 8% 5% 4 4 4 5% 7% 36%	120723
	Night	15% 10% 4 8% 5% 4 4 3 5% 7% 36%	118094
Transparency	Day	45% 6% 11% 22% 14% 2	124407
	Night	46% 6% 11% 22% 14% 2	122535
Seeing	Day	18% 12% 26% 23% 15% 6%	16128
	Night	18% 9% 27% 29% 15% 2	25649

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% 9% 13% 5% 4 3 3 4 5% 24%	4056
	11th to 20th	Day	13% 15% 6% 15% 6% 7% 4 3 3 4 24%	4060
	21st to end	Day	22% 12% 7% 9% 6% 5% 4 3 4 5% 23%	4466
February	1st to 10th	Day	19% 13% 5% 9% 5% 4 4 4 4 5% 27%	1880
	11th to 20th	Day	17% 11% 5% 11% 6% 5% 3 3 4 5% 29%	1948
	21st to end	Day	17% 15% 4 9% 4 4 3 3 4 6% 30%	1650
March	1st to 10th	Day	17% 14% 6% 9% 4 4 3 3 4 5% 30%	4564
	11th to 20th	Day	13% 8% 3 7% 5% 4 4 4 5% 8% 39%	4980
	21st to end	Day	17% 10% 3 7% 5% 4 4 3 5% 7% 34%	5465
April	1st to 10th	Day	16% 8% 4 7% 5% 5% 4 4 6% 7% 35%	2330
	11th to 20th	Day	16% 8% 2 8% 5% 5% 4 4 5% 6% 39%	2447
	21st to end	Day	17% 9% 3 7% 5% 4 5% 4 5% 7% 35%	2600
May	1st to 10th	Day	20% 8% 3 8% 5% 4 5% 4 6% 8% 29%	5862
	11th to 20th	Day	19% 8% 3 8% 5% 4 4 4 5% 7% 33%	5861
	21st to end	Day	14% 6% 2 7% 5% 5% 6% 5% 7% 9% 33%	6433
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 6% 5% 6% 8% 40%	2600
	11th to 20th	Day	9% 6% 2 7% 5% 5% 5% 4 6% 10% 42%	2729
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 4 7% 10% 41%	2800
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 4 7% 9% 39%	4511
	11th to 20th	Day	7% 5% 2 6% 4 4 5% 4 7% 12% 45%	4184
	21st to end	Day	11% 7% 3 8% 6% 6% 6% 5% 7% 9% 31%	4466
August	1st to 10th	Day	8% 6% 2 5% 4 4 5% 4 7% 10% 44%	4104
	11th to 20th	Day	7% 7% 2 6% 4 5% 6% 5% 7% 10% 41%	4044
	21st to end	Day	6% 4 2 5% 3 4 4 3 5% 9% 55%	4255
September	1st to 10th	Day	12% 5% 2 6% 4 4 4 3 5% 7% 49%	2145
	11th to 20th	Day	9% 5% 2 5% 3 4 4 4 7% 9% 48%	2090
	21st to end	Day	16% 6% 2 6% 4 4 3 2 5% 6% 46%	2090
October	1st to 10th	Day	11% 5% 2 5% 4 4 5% 4 5% 6% 50%	2090
	11th to 20th	Day	14% 7% 2 6% 4 4 5% 2 5% 7% 46%	1911
	21st to end	Day	19% 9% 3 6% 4 3 3 3 4 7% 39%	1971
November	1st to 10th	Day	10% 7% 2 6% 3 3 4 3 5% 6% 51%	1762
	11th to 20th	Day	14% 11% 4 8% 5% 4 4 4 5% 5% 36%	1800
	21st to end	Day	17% 11% 4 8% 4 5% 3 3 4 6% 35%	1800
December	1st to 10th	Day	18% 10% 4 8% 5% 3 4 3 3 5% 37%	2930
	11th to 20th	Day	19% 13% 5% 10% 5% 5% 5% 4 5% 5% 25%	3373
	21st to end	Day	22% 19% 5% 10% 5% 5% 4 3 4 5% 19%	4466
January	1st to 10th	Night	14% 16% 7% 15% 8% 5% 4 4 4 5% 19%	5889
	11th to 20th	Night	15% 15% 7% 13% 8% 5% 5% 3 4 5% 21%	5900
	21st to end	Night	20% 13% 5% 8% 4 4 3 3 4 5% 30%	6490
February	1st to 10th	Night	21% 13% 4 8% 5% 4 4 3 5% 5% 28%	2515
	11th to 20th	Night	19% 11% 4 9% 4 5% 4 3 5% 6% 30%	2338
	21st to end	Night	20% 14% 5% 7% 4 4 3 3 4 6% 31%	1980
March	1st to 10th	Night	19% 12% 3 7% 4 4 3 3 4 5% 37%	5289
	11th to 20th	Night	12% 7% 2 6% 4 4 5% 3 6% 8% 42%	4980
	21st to end	Night	18% 9% 4 8% 5% 4 4 3 5% 5% 34%	5467
April	1st to 10th	Night	16% 9% 3 6% 4 4 5% 4 6% 6% 37%	2087
	11th to 20th	Night	14% 8% 2 5% 4 4 4 4 6% 7% 41%	1900
	21st to end	Night	17% 7% 3 6% 4 5% 4 4 7% 7% 37%	1800
May	1st to 10th	Night	21% 10% 3 8% 5% 4 5% 4 6% 7% 27%	4033
	11th to 20th	Night	16% 7% 3 7% 4 4 5% 5% 7% 9% 34%	4032
	21st to end	Night	13% 6% 2 6% 5% 4 5% 4 6% 9% 39%	4421
June	1st to 10th	Night	9% 5% 2 5% 4 4 4 4 6% 8% 50%	1800
	11th to 20th	Night	9% 4 2 5% 4 3 5% 4 7% 11% 46%	1663
	21st to end	Night	6% 3 2 5% 4 5% 5% 6% 7% 10% 47%	1600
July	1st to 10th	Night	9% 5% 2 6% 3 4 4 3 5% 8% 50%	2570
	11th to 20th	Night	6% 5% 2 5% 4 4 5% 4 6% 10% 50%	2773
	21st to end	Night	11% 6% 3 8% 5% 5% 5% 4 6% 9% 38%	3087
August	1st to 10th	Night	8% 7% 3 7% 4 4 5% 4 6% 8% 44%	2825
	11th to 20th	Night	8% 7% 3 8% 4 4 4 3 6% 8% 46%	2785
	21st to end	Night	4 2 1 4 3 4 4 4 7% 10% 58%	3398
September	1st to 10th	Night	11% 5% 2 5% 4 3 4 3 5% 7% 52%	2015
	11th to 20th	Night	8% 5% 2 5% 4 3 4 4 5% 7% 54%	2090
	21st to end	Night	14% 6% 2 5% 4 4 3 3 3 6% 49%	2090
October	1st to 10th	Night	9% 4 2 6% 3 4 3 3 5% 6% 55%	2090
	11th to 20th	Night	14% 7% 2 6% 4 4 4 4 5% 7% 45%	2267
	21st to end	Night	18% 8% 2 5% 4 4 3 4 5% 6% 41%	2622
November	1st to 10th	Night	14% 7% 2 5% 4 4 3 3 5% 6% 46%	2536
	11th to 20th	Night	15% 9% 3 7% 4 4 4 3 5% 7% 39%	2600
	21st to end	Night	18% 14% 3 7% 5% 4 4 3 5% 6% 32%	2600
December	1st to 10th	Night	16% 11% 4 8% 4 4 3 3 4 5% 37%	4250
	11th to 20th	Night	19% 14% 6% 9% 5% 5% 4 3 4 6% 26%	4822
	21st to end	Night	21% 18% 7% 11% 6% 5% 4 3 4 5% 17%	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	64% 4 10% 16% 7%	4057
	11th to 20th	Day	62% 6% 8% 12% 10% 2	4060
	21st to end	Day	64% 3 10% 15% 6% 2	4466
February	1st to 10th	Day	58% 4 10% 17% 9% 1	1880
	11th to 20th	Day	57% 5% 10% 17% 10% 1	1958
	21st to end	Day	56% 5% 9% 20% 9% 1	1650
March	1st to 10th	Day	55% 5% 8% 19% 12% 2	4564
	11th to 20th	Day	42% 6% 9% 27% 15% 1	4980
	21st to end	Day	49% 5% 12% 20% 12% 2	5465
April	1st to 10th	Day	47% 8% 11% 22% 12% 1	2330
	11th to 20th	Day	45% 6% 10% 22% 13% 3	2447
	21st to end	Day	48% 7% 11% 21% 11% 2	2600
May	1st to 10th	Day	51% 8% 13% 18% 10% 1	5897
	11th to 20th	Day	50% 6% 12% 23% 9%	5865
	21st to end	Day	42% 10% 13% 22% 12% 1	6447
June	1st to 10th	Day	39% 9% 12% 23% 16% 2	2600
	11th to 20th	Day	36% 9% 14% 23% 16% 1	2729
	21st to end	Day	37% 9% 15% 21% 14% 4	2800
July	1st to 10th	Day	41% 7% 12% 21% 18% 2	4442
	11th to 20th	Day	30% 7% 12% 32% 17% 1	4113
	21st to end	Day	46% 8% 13% 17% 12% 3	4324
August	1st to 10th	Day	33% 9% 16% 32% 10% 1	4091
	11th to 20th	Day	35% 7% 12% 31% 15%	4083
	21st to end	Day	26% 7% 14% 29% 20% 3	4254
September	1st to 10th	Day	34% 6% 11% 23% 20% 5%	2145
	11th to 20th	Day	31% 7% 13% 24% 22% 3	2090
	21st to end	Day	39% 6% 10% 23% 21% 2	2090
October	1st to 10th	Day	23% 5% 8% 30% 32% 2	3480
	11th to 20th	Day	30% 4 9% 30% 26% 2	3151
	21st to end	Day	35% 3 11% 24% 24% 3	3221
November	1st to 10th	Day	34% 5% 11% 28% 20% 3	1762
	11th to 20th	Day	49% 5% 8% 21% 15% 3	1800
	21st to end	Day	51% 4 10% 21% 13% 1	1800
December	1st to 10th	Day	51% 4 10% 26% 10%	2930
	11th to 20th	Day	62% 5% 8% 17% 7%	3370
	21st to end	Day	67% 5% 10% 12% 5% 1	4466
January	1st to 10th	Night	66% 6% 8% 13% 7%	5889
	11th to 20th	Night	66% 4 8% 12% 7% 3	5900
	21st to end	Night	56% 4 9% 20% 9% 1	6490
February	1st to 10th	Night	57% 5% 11% 18% 8% 1	2515
	11th to 20th	Night	55% 5% 10% 18% 11% 1	2339
	21st to end	Night	55% 5% 10% 17% 11% 2	1980
March	1st to 10th	Night	50% 4 6% 26% 11% 2	5289
	11th to 20th	Night	37% 6% 12% 28% 16% 1	4980
	21st to end	Night	51% 5% 8% 24% 11% 2	5467
April	1st to 10th	Night	45% 8% 11% 22% 12% 2	2087
	11th to 20th	Night	40% 7% 12% 19% 17% 5%	1900
	21st to end	Night	44% 7% 10% 21% 14% 3	1800
May	1st to 10th	Night	54% 8% 9% 17% 7% 3	4060
	11th to 20th	Night	44% 9% 14% 23% 9% 1	4033
	21st to end	Night	39% 8% 17% 22% 11% 3	4429
June	1st to 10th	Night	31% 8% 12% 26% 21% 2	1800
	11th to 20th	Night	29% 10% 16% 22% 19% 4	1663
	21st to end	Night	28% 11% 17% 22% 17% 5%	1600
July	1st to 10th	Night	33% 7% 11% 24% 20% 5%	2530
	11th to 20th	Night	28% 7% 13% 31% 19% 2	2722
	21st to end	Night	41% 6% 13% 21% 14% 4	2988
August	1st to 10th	Night	35% 8% 14% 31% 12% 1	2814
	11th to 20th	Night	36% 7% 12% 26% 18% 1	2812
	21st to end	Night	20% 7% 16% 32% 22% 3	3398
September	1st to 10th	Night	31% 7% 12% 24% 18% 7%	2015
	11th to 20th	Night	28% 8% 11% 23% 28% 3	2090
	21st to end	Night	37% 5% 10% 21% 25% 2	2090
October	1st to 10th	Night	22% 4 8% 26% 38% 3	3480
	11th to 20th	Night	27% 4 9% 26% 31% 3	3766
	21st to end	Night	32% 4 9% 23% 27% 5%	4309
November	1st to 10th	Night	38% 5% 10% 22% 21% 4	2536
	11th to 20th	Night	44% 5% 9% 20% 18% 3	2600
	21st to end	Night	53% 4 10% 20% 11% 2	2600
December	1st to 10th	Night	50% 4 11% 24% 10%	4250
	11th to 20th	Night	59% 5% 11% 18% 7% 1	4824
	21st to end	Night	69% 6% 8% 14% 4	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	23% 24% 35% 14% 4	300
	11th to 20th	Day	25% 23% 37% 12% 3	300
	21st to end	Day	30% 20% 35% 13% 2	330
February	1st to 10th	Day	28% 23% 33% 14% 3	300
	11th to 20th	Day	30% 25% 34% 10% 2	300
	21st to end	Day	29% 17% 44% 9% 1	249
March	1st to 10th	Day	21% 27% 35% 14% 3	332
	11th to 20th	Day	23% 17% 37% 17% 6%	500
	21st to end	Day	28% 20% 30% 17% 5%	550
April	1st to 10th	Day	21% 19% 30% 21% 9% 1	500
	11th to 20th	Day	21% 20% 26% 21% 11% 3	492
	21st to end	Day	21% 15% 34% 18% 10% 2	500
May	1st to 10th	Day	23% 14% 32% 20% 8% 4	503
	11th to 20th	Day	21% 10% 25% 25% 13% 6%	527
	21st to end	Day	15% 6% 27% 26% 18% 9%	573
June	1st to 10th	Day	12% 6% 22% 30% 22% 7%	530
	11th to 20th	Day	12% 5% 20% 32% 23% 7%	659
	21st to end	Day	10% 4 23% 31% 22% 10%	730
July	1st to 10th	Day	13% 4 16% 24% 23% 20%	697
	11th to 20th	Day	9% 3 20% 29% 26% 12%	520
	21st to end	Day	11% 3 16% 30% 26% 14%	532
August	1st to 10th	Day	12% 3 12% 27% 30% 15%	486
	11th to 20th	Day	11% 4 20% 30% 23% 12%	479
	21st to end	Day	8% 4 13% 28% 30% 16%	539
September	1st to 10th	Day	11% 3 18% 28% 29% 12%	490
	11th to 20th	Day	11% 3 15% 25% 32% 14%	490
	21st to end	Day	19% 8% 20% 24% 21% 7%	490
October	1st to 10th	Day	9% 6% 24% 33% 20% 8%	490
	11th to 20th	Day	16% 14% 31% 21% 13% 4	490
	21st to end	Day	21% 14% 34% 23% 7%	420
November	1st to 10th	Day	16% 11% 35% 24% 11% 3	300
	11th to 20th	Day	21% 21% 29% 20% 7% 2	300
	21st to end	Day	23% 15% 40% 19% 3	300
December	1st to 10th	Day	21% 21% 37% 16% 5% 1	300
	11th to 20th	Day	20% 21% 40% 15% 5%	300
	21st to end	Day	29% 19% 34% 15% 3	330
January	1st to 10th	Night	20% 20% 34% 21% 4	800
	11th to 20th	Night	27% 16% 35% 19% 3	800
	21st to end	Night	23% 16% 35% 24% 3	880
February	1st to 10th	Night	28% 12% 35% 24% 2	800
	11th to 20th	Night	25% 16% 37% 20% 2	783
	21st to end	Night	27% 13% 38% 21% 1	660
March	1st to 10th	Night	22% 14% 35% 24% 5%	800
	11th to 20th	Night	22% 14% 35% 22% 6% 1	800
	21st to end	Night	24% 10% 34% 26% 6%	880
April	1st to 10th	Night	20% 14% 33% 26% 7%	687
	11th to 20th	Night	17% 12% 32% 27% 11% 1	593
	21st to end	Night	18% 8% 38% 27% 8% 1	600
May	1st to 10th	Night	21% 8% 31% 28% 11% 1	600
	11th to 20th	Night	17% 5% 25% 34% 18% 2	591
	21st to end	Night	10% 2 23% 37% 22% 6%	650
June	1st to 10th	Night	9% 3 20% 43% 23% 1	600
	11th to 20th	Night	11% 4 14% 42% 27% 3	600
	21st to end	Night	7% 2 19% 43% 27% 3	600
July	1st to 10th	Night	11% 2 12% 33% 32% 10%	570
	11th to 20th	Night	7% 2 13% 37% 36% 4	552
	21st to end	Night	11% 2 11% 40% 33% 4	624
August	1st to 10th	Night	9% 2 10% 40% 35% 4	567
	11th to 20th	Night	10% 1 12% 43% 29% 5%	564
	21st to end	Night	7% 1 13% 34% 37% 8%	627
September	1st to 10th	Night	14% 1 14% 32% 33% 5%	685
	11th to 20th	Night	10% 2 15% 35% 33% 6%	760
	21st to end	Night	16% 5% 22% 32% 24% 2	760
October	1st to 10th	Night	11% 4 22% 36% 23% 3	760
	11th to 20th	Night	17% 9% 27% 32% 14% 1	760
	21st to end	Night	22% 8% 33% 27% 11%	836
November	1st to 10th	Night	18% 8% 30% 28% 15% 1	780
	11th to 20th	Night	18% 15% 32% 25% 9% 1	800
	21st to end	Night	25% 13% 27% 28% 7% 1	800
December	1st to 10th	Night	25% 13% 34% 23% 5%	800
	11th to 20th	Night	26% 11% 34% 23% 6% 1	800
	21st to end	Night	29% 14% 31% 22% 3	880

Page generated at 2025-07-03 01:30:13. Version ac07

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