High Cliff State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the High Cliff State Park clear sky chart from 2005-11-06 to 2025-11-03.

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	12% 8% 3 8% 5% 4 5% 4 6% 7% 38%	126927
	Night	12% 10% 4 8% 5% 4 4 3 5% 6% 39%	123381
Transparency	Day	43% 6% 12% 25% 13% 1	130401
	Night	44% 6% 12% 23% 14% 2	127981
Seeing	Day	16% 10% 30% 26% 13% 4	17342
	Night	17% 9% 32% 30% 11% 1	27165

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	8% 10% 4 16% 7% 5% 5% 3 5% 5% 31%	3617
	11th to 20th	Day	9% 10% 5% 12% 5% 5% 8% 5% 6% 7% 28%	3620
	21st to end	Day	12% 13% 5% 13% 5% 4 4 3 4 5% 31%	3982
February	1st to 10th	Day	10% 12% 5% 12% 6% 5% 5% 4 5% 7% 31%	1780
	11th to 20th	Day	11% 11% 3 8% 5% 4 5% 3 5% 7% 37%	1912
	21st to end	Day	12% 13% 4 9% 6% 5% 4 3 5% 6% 33%	1650
March	1st to 10th	Day	13% 7% 2 6% 4 3 4 3 6% 7% 45%	4480
	11th to 20th	Day	11% 7% 2 7% 5% 4 4 4 6% 8% 42%	4687
	21st to end	Day	23% 12% 4 9% 4 4 4 3 4 5% 28%	5967
April	1st to 10th	Day	15% 14% 3 7% 5% 5% 5% 4 5% 7% 30%	2400
	11th to 20th	Day	19% 10% 3 6% 5% 5% 4 3 5% 6% 35%	2374
	21st to end	Day	17% 10% 2 8% 5% 4 4 4 6% 7% 33%	2551
May	1st to 10th	Day	12% 7% 2 6% 4 4 4 4 5% 7% 43%	5995
	11th to 20th	Day	11% 6% 2 7% 4 4 5% 4 6% 8% 43%	6319
	21st to end	Day	15% 7% 2 6% 4 4 5% 3 6% 8% 40%	6935
June	1st to 10th	Day	10% 6% 2 7% 5% 4 4 4 6% 9% 43%	2800
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 6% 10% 40%	2800
	21st to end	Day	10% 6% 2 6% 4 4 5% 4 7% 10% 42%	2800
July	1st to 10th	Day	11% 6% 2 6% 4 4 5% 5% 7% 10% 40%	6360
	11th to 20th	Day	6% 4 2 4 3 4 4 5% 8% 10% 50%	6360
	21st to end	Day	8% 6% 2 6% 4 5% 5% 4 7% 9% 45%	6924
August	1st to 10th	Day	8% 6% 2 7% 5% 5% 5% 5% 6% 9% 42%	4563
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 6% 8% 46%	4021
	21st to end	Day	10% 7% 2 7% 5% 5% 5% 4 6% 8% 41%	4312
September	1st to 10th	Day	11% 5% 2 7% 4 4 5% 4 5% 7% 46%	2400
	11th to 20th	Day	11% 5% 2 5% 4 4 4 3 5% 9% 48%	2290
	21st to end	Day	12% 8% 3 7% 5% 4 4 4 6% 7% 41%	2200
October	1st to 10th	Day	13% 7% 2 6% 4 4 4 3 5% 6% 46%	2105
	11th to 20th	Day	19% 10% 4 7% 6% 5% 3 4 6% 7% 29%	1957
	21st to end	Day	16% 11% 3 8% 4 4 4 4 4 6% 37%	1980
November	1st to 10th	Day	13% 9% 3 6% 4 4 5% 3 4 7% 41%	1780
	11th to 20th	Day	11% 13% 5% 10% 6% 5% 5% 4 6% 6% 29%	1800
	21st to end	Day	15% 12% 4 9% 5% 4 4 3 3 6% 33%	1606
December	1st to 10th	Day	8% 11% 5% 11% 8% 6% 6% 5% 7% 6% 29%	2610
	11th to 20th	Day	11% 16% 5% 14% 6% 5% 4 3 4 5% 26%	3008
	21st to end	Day	18% 19% 6% 14% 7% 4 4 3 4 4 17%	3982
January	1st to 10th	Night	9% 13% 6% 11% 6% 4 3 3 4 5% 37%	6348
	11th to 20th	Night	10% 12% 5% 14% 6% 5% 7% 5% 5% 5% 26%	6360
	21st to end	Night	10% 14% 6% 12% 5% 6% 4 3 4 5% 31%	6996
February	1st to 10th	Night	10% 14% 4 9% 6% 5% 5% 4 5% 6% 33%	2616
	11th to 20th	Night	10% 9% 4 9% 6% 6% 5% 3 4 4 39%	2373
	21st to end	Night	15% 12% 3 8% 4 4 4 3 5% 4 37%	1980
March	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 5% 6% 46%	5373
	11th to 20th	Night	9% 8% 3 7% 5% 5% 5% 4 5% 8% 41%	5315
	21st to end	Night	20% 11% 4 9% 5% 4 4 4 4 5% 31%	4962
April	1st to 10th	Night	18% 10% 4 7% 5% 4 4 2 5% 6% 35%	2000
	11th to 20th	Night	20% 8% 3 6% 5% 3 3 4 6% 6% 37%	1975
	21st to end	Night	17% 7% 2 8% 5% 5% 4 3 5% 6% 38%	1847
May	1st to 10th	Night	14% 7% 3 6% 4 4 3 3 5% 8% 42%	3902
	11th to 20th	Night	9% 5% 2 7% 4 4 5% 4 6% 8% 43%	3596
	21st to end	Night	18% 8% 3 7% 4 4 4 4 5% 6% 37%	3942
June	1st to 10th	Night	9% 6% 2 5% 5% 5% 4 4 7% 7% 47%	1600
	11th to 20th	Night	13% 7% 2 7% 4 3 4 4 7% 8% 43%	1600
	21st to end	Night	9% 5% 2 5% 5% 4 5% 4 6% 9% 46%	1600
July	1st to 10th	Night	11% 6% 2 6% 3 4 5% 4 6% 8% 45%	3618
	11th to 20th	Night	7% 5% 2 5% 3 4 4 4 5% 7% 54%	3617
	21st to end	Night	5% 5% 2 6% 4 4 5% 4 7% 9% 51%	3947
August	1st to 10th	Night	11% 5% 3 5% 4 4 4 4 5% 8% 48%	2597
	11th to 20th	Night	11% 7% 2 7% 4 4 4 3 5% 7% 47%	3023
	21st to end	Night	8% 5% 2 5% 4 4 4 4 6% 8% 49%	3586
September	1st to 10th	Night	9% 5% 2 5% 4 3 4 3 5% 7% 53%	2000
	11th to 20th	Night	12% 5% 1 5% 3 4 4 3 4 7% 53%	2089
	21st to end	Night	11% 6% 3 5% 4 4 4 3 6% 7% 47%	2200
October	1st to 10th	Night	12% 6% 2 5% 4 4 4 3 5% 6% 49%	2290
	11th to 20th	Night	15% 8% 3 7% 4 4 5% 4 5% 7% 38%	2441
	21st to end	Night	17% 10% 3 7% 4 4 4 3 5% 7% 36%	2860
November	1st to 10th	Night	13% 8% 3 5% 5% 4 4 4 4 6% 45%	2563
	11th to 20th	Night	14% 12% 5% 9% 6% 5% 4 3 5% 5% 33%	2600
	21st to end	Night	15% 11% 3 8% 6% 4 4 3 4 6% 36%	2790
December	1st to 10th	Night	9% 10% 4 8% 5% 4 5% 4 6% 8% 36%	4580
	11th to 20th	Night	13% 18% 7% 11% 5% 4 4 3 4 5% 28%	5199
	21st to end	Night	19% 17% 6% 11% 6% 5% 4 3 4 5% 21%	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	54% 6% 15% 18% 7%	3618
	11th to 20th	Day	54% 6% 10% 18% 12% 1	3620
	21st to end	Day	55% 5% 9% 20% 11%	3982
February	1st to 10th	Day	52% 5% 12% 20% 10% 1	1780
	11th to 20th	Day	46% 6% 11% 24% 12% 1	1922
	21st to end	Day	51% 6% 11% 20% 10% 2	1650
March	1st to 10th	Day	37% 5% 14% 22% 16% 5%	4480
	11th to 20th	Day	38% 6% 16% 24% 14% 2	4687
	21st to end	Day	59% 5% 9% 17% 10%	5969
April	1st to 10th	Day	53% 7% 11% 19% 10%	2400
	11th to 20th	Day	49% 6% 9% 21% 12% 2	2374
	21st to end	Day	49% 7% 12% 19% 12% 2	2551
May	1st to 10th	Day	37% 7% 13% 25% 16% 3	6030
	11th to 20th	Day	37% 7% 12% 28% 16% 1	6323
	21st to end	Day	40% 7% 10% 26% 14% 2	6949
June	1st to 10th	Day	37% 7% 12% 28% 15% 2	2800
	11th to 20th	Day	39% 7% 14% 26% 14% 1	2800
	21st to end	Day	35% 9% 14% 25% 15% 1	2800
July	1st to 10th	Day	37% 7% 13% 32% 10% 1	6291
	11th to 20th	Day	26% 8% 17% 33% 15% 1	6285
	21st to end	Day	34% 8% 14% 25% 18% 2	6728
August	1st to 10th	Day	36% 7% 16% 28% 12% 1	4548
	11th to 20th	Day	33% 7% 13% 35% 11% 1	4060
	21st to end	Day	39% 6% 14% 24% 16% 1	4311
September	1st to 10th	Day	37% 7% 13% 28% 15% 1	2400
	11th to 20th	Day	33% 6% 15% 32% 12% 1	2290
	21st to end	Day	41% 6% 12% 30% 11%	2200
October	1st to 10th	Day	25% 4 9% 37% 24% 1	3430
	11th to 20th	Day	44% 6% 9% 26% 15% 1	3160
	21st to end	Day	43% 5% 13% 27% 12%	3180
November	1st to 10th	Day	43% 5% 13% 24% 13% 1	1780
	11th to 20th	Day	54% 6% 15% 17% 8%	1800
	21st to end	Day	53% 5% 15% 20% 6% 1	1606
December	1st to 10th	Day	54% 8% 15% 20% 3	2610
	11th to 20th	Day	59% 5% 10% 17% 8% 1	3005
	21st to end	Day	71% 5% 6% 11% 7%	3982
January	1st to 10th	Night	50% 4 9% 24% 12% 1	6348
	11th to 20th	Night	58% 5% 9% 13% 14% 1	6360
	21st to end	Night	55% 5% 12% 16% 11%	6996
February	1st to 10th	Night	52% 5% 9% 21% 11% 2	2616
	11th to 20th	Night	48% 5% 10% 24% 12% 2	2374
	21st to end	Night	50% 4 13% 20% 11% 2	1980
March	1st to 10th	Night	38% 4 16% 25% 13% 3	5373
	11th to 20th	Night	40% 6% 17% 23% 13% 2	5315
	21st to end	Night	54% 6% 9% 17% 12% 1	4962
April	1st to 10th	Night	50% 6% 7% 18% 18% 1	2000
	11th to 20th	Night	47% 5% 9% 22% 14% 3	1975
	21st to end	Night	46% 6% 11% 21% 14% 2	1847
May	1st to 10th	Night	39% 6% 13% 20% 20% 2	3929
	11th to 20th	Night	35% 8% 15% 23% 17% 2	3597
	21st to end	Night	47% 6% 9% 23% 11% 4	3950
June	1st to 10th	Night	35% 7% 12% 30% 16% 1	1600
	11th to 20th	Night	38% 7% 11% 26% 17% 2	1600
	21st to end	Night	32% 9% 17% 24% 15% 4	1600
July	1st to 10th	Night	35% 5% 16% 31% 9% 4	3580
	11th to 20th	Night	27% 6% 15% 32% 16% 2	3572
	21st to end	Night	28% 7% 15% 26% 23% 2	3832
August	1st to 10th	Night	34% 6% 14% 27% 19% 2	2588
	11th to 20th	Night	36% 6% 12% 30% 15% 1	3050
	21st to end	Night	31% 6% 15% 24% 21% 2	3586
September	1st to 10th	Night	31% 6% 12% 27% 22% 2	2000
	11th to 20th	Night	31% 6% 12% 34% 16% 1	2089
	21st to end	Night	36% 5% 12% 29% 16% 1	2200
October	1st to 10th	Night	28% 4 8% 38% 21% 2	3745
	11th to 20th	Night	34% 5% 13% 30% 15% 2	3977
	21st to end	Night	44% 5% 11% 24% 16%	4610
November	1st to 10th	Night	40% 5% 13% 25% 15% 2	2563
	11th to 20th	Night	53% 5% 12% 18% 10% 1	2600
	21st to end	Night	50% 5% 15% 23% 6% 1	2790
December	1st to 10th	Night	45% 7% 21% 20% 5% 2	4580
	11th to 20th	Night	61% 4 9% 13% 12% 1	5201
	21st to end	Night	65% 6% 8% 14% 7%	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	15% 13% 37% 25% 8% 1	300
	11th to 20th	Day	17% 14% 37% 27% 5% 1	300
	21st to end	Day	18% 15% 34% 25% 6% 1	330
February	1st to 10th	Day	14% 16% 42% 20% 7% 1	300
	11th to 20th	Day	14% 20% 41% 17% 8%	300
	21st to end	Day	18% 18% 45% 17% 2	249
March	1st to 10th	Day	16% 15% 45% 19% 5%	300
	11th to 20th	Day	23% 16% 31% 21% 7% 2	316
	21st to end	Day	26% 12% 29% 24% 7% 1	550
April	1st to 10th	Day	25% 14% 33% 22% 5%	500
	11th to 20th	Day	26% 17% 29% 17% 9% 2	492
	21st to end	Day	21% 14% 29% 24% 10% 3	500
May	1st to 10th	Day	19% 11% 33% 26% 10% 2	558
	11th to 20th	Day	16% 12% 31% 27% 10% 3	725
	21st to end	Day	17% 9% 30% 26% 14% 4	789
June	1st to 10th	Day	11% 10% 32% 30% 13% 4	730
	11th to 20th	Day	17% 7% 34% 27% 12% 3	730
	21st to end	Day	14% 9% 29% 30% 15% 3	730
July	1st to 10th	Day	10% 4 21% 33% 24% 8%	721
	11th to 20th	Day	10% 6% 26% 32% 19% 7%	718
	21st to end	Day	8% 4 26% 33% 21% 8%	794
August	1st to 10th	Day	8% 4 26% 32% 21% 9%	726
	11th to 20th	Day	12% 4 19% 28% 26% 11%	547
	21st to end	Day	15% 5% 20% 30% 21% 9%	583
September	1st to 10th	Day	14% 9% 22% 27% 20% 9%	530
	11th to 20th	Day	10% 4 20% 35% 20% 9%	530
	21st to end	Day	15% 10% 24% 28% 18% 5%	530
October	1st to 10th	Day	17% 11% 24% 27% 17% 3	435
	11th to 20th	Day	18% 18% 32% 24% 8%	330
	21st to end	Day	23% 13% 38% 19% 6% 2	363
November	1st to 10th	Day	17% 15% 35% 24% 9% 1	306
	11th to 20th	Day	17% 17% 39% 18% 8%	300
	21st to end	Day	23% 15% 41% 14% 6%	300
December	1st to 10th	Day	19% 15% 43% 19% 5%	300
	11th to 20th	Day	21% 15% 42% 15% 5% 2	300
	21st to end	Day	27% 12% 38% 15% 6% 1	330
January	1st to 10th	Night	16% 14% 38% 26% 6%	1000
	11th to 20th	Night	20% 12% 39% 23% 6% 1	1000
	21st to end	Night	19% 9% 38% 27% 6%	1100
February	1st to 10th	Night	17% 13% 37% 26% 6%	1000
	11th to 20th	Night	15% 14% 39% 25% 7%	818
	21st to end	Night	22% 12% 36% 26% 4	660
March	1st to 10th	Night	19% 10% 35% 27% 8% 1	800
	11th to 20th	Night	16% 13% 37% 29% 6% 1	770
	21st to end	Night	21% 7% 32% 31% 9%	660
April	1st to 10th	Night	22% 9% 38% 25% 5%	600
	11th to 20th	Night	23% 12% 32% 26% 7% 1	593
	21st to end	Night	20% 8% 34% 30% 8% 1	600
May	1st to 10th	Night	21% 8% 32% 32% 8%	600
	11th to 20th	Night	18% 6% 36% 31% 9%	591
	21st to end	Night	14% 6% 27% 38% 14% 1	650
June	1st to 10th	Night	10% 6% 32% 40% 13% 1	600
	11th to 20th	Night	16% 5% 31% 36% 11% 1	600
	21st to end	Night	11% 4 28% 42% 15% 1	600
July	1st to 10th	Night	9% 2 20% 46% 22% 2	585
	11th to 20th	Night	9% 3 22% 41% 23% 2	582
	21st to end	Night	6% 2 22% 46% 23% 1	657
August	1st to 10th	Night	9% 2 16% 45% 25% 2	597
	11th to 20th	Night	10% 2 18% 41% 25% 4	594
	21st to end	Night	10% 3 22% 40% 24% 2	660
September	1st to 10th	Night	11% 5% 24% 36% 20% 5%	600
	11th to 20th	Night	14% 4 21% 33% 23% 4	689
	21st to end	Night	13% 8% 25% 32% 20% 2	800
October	1st to 10th	Night	15% 8% 28% 32% 16% 1	800
	11th to 20th	Night	19% 12% 35% 26% 7%	800
	21st to end	Night	23% 10% 31% 26% 9% 1	880
November	1st to 10th	Night	17% 10% 39% 26% 8% 1	789
	11th to 20th	Night	21% 16% 35% 23% 5%	800
	21st to end	Night	20% 14% 37% 22% 7%	990
December	1st to 10th	Night	20% 15% 38% 21% 6%	1000
	11th to 20th	Night	22% 13% 37% 22% 5% 1	1000
	21st to end	Night	25% 13% 36% 22% 4	1100

Page generated at 2025-10-31 01:02:37. Version ac07

Copyright © 2025 Attilla Danko.