Cuivre River State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cuivre River State Park clear sky chart from 2005-11-06 to 2026-01-17.

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% 7% 3 7% 4 4 4 4 5% 7% 42%	127428
	Night	13% 8% 3 7% 4 4 4 3 5% 7% 43%	124526
Transparency	Day	40% 3 11% 26% 17% 2	131021
	Night	42% 2 10% 25% 18% 3	129010
Seeing	Day	15% 8% 24% 27% 19% 6%	17258
	Night	16% 7% 27% 33% 15% 1	27153

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	13% 12% 6% 13% 5% 4 4 4 4 6% 30%	3697
	11th to 20th	Day	9% 10% 4 9% 6% 6% 4 3 5% 7% 39%	4011
	21st to end	Day	17% 14% 6% 7% 4 3 3 2 4 4 35%	4488
February	1st to 10th	Day	16% 11% 5% 8% 4 4 4 3 4 6% 34%	1800
	11th to 20th	Day	15% 9% 3 8% 4 5% 4 4 5% 6% 37%	1887
	21st to end	Day	15% 12% 3 7% 4 3 3 3 4 5% 41%	1650
March	1st to 10th	Day	15% 11% 2 5% 3 3 3 2 3 4 50%	4632
	11th to 20th	Day	9% 7% 2 4 3 4 5% 3 6% 7% 51%	4980
	21st to end	Day	15% 8% 3 7% 5% 4 5% 4 6% 7% 35%	5708
April	1st to 10th	Day	14% 8% 2 7% 5% 4 5% 3 5% 6% 42%	2400
	11th to 20th	Day	17% 9% 2 6% 4 3 4 3 5% 5% 41%	2374
	21st to end	Day	18% 7% 3 7% 5% 4 3 4 5% 8% 37%	2400
May	1st to 10th	Day	15% 8% 3 8% 5% 4 5% 4 6% 9% 33%	5572
	11th to 20th	Day	15% 7% 3 7% 4 4 4 3 5% 8% 38%	6319
	21st to end	Day	14% 7% 3 6% 4 4 4 4 6% 7% 41%	6935
June	1st to 10th	Day	8% 5% 2 5% 3 5% 4 5% 7% 9% 48%	2800
	11th to 20th	Day	8% 5% 1 5% 4 5% 4 4 7% 8% 49%	2800
	21st to end	Day	6% 4 2 5% 5% 5% 5% 5% 8% 9% 47%	2800
July	1st to 10th	Day	10% 5% 2 5% 4 4 4 3 6% 10% 46%	6360
	11th to 20th	Day	7% 5% 3 7% 5% 5% 6% 4 7% 10% 41%	6360
	21st to end	Day	7% 5% 2 6% 5% 6% 6% 5% 8% 11% 38%	6522
August	1st to 10th	Day	5% 4 2 5% 3 5% 5% 5% 7% 9% 50%	4234
	11th to 20th	Day	14% 4 2 6% 4 4 4 4 6% 8% 43%	3894
	21st to end	Day	6% 4 2 5% 4 4 5% 3 6% 11% 50%	4312
September	1st to 10th	Day	12% 5% 1 5% 4 3 3 3 4 7% 53%	2400
	11th to 20th	Day	9% 4 2 5% 4 3 4 3 6% 8% 51%	2398
	21st to end	Day	8% 5% 2 5% 4 4 4 3 5% 7% 53%	2150
October	1st to 10th	Day	10% 4 2 5% 3 3 3 2 5% 6% 56%	2000
	11th to 20th	Day	15% 7% 2 5% 3 3 2 3 3 5% 53%	2000
	21st to end	Day	17% 9% 2 5% 3 3 3 2 4 4 47%	2200
November	1st to 10th	Day	12% 6% 2 4 3 3 3 3 5% 6% 54%	1854
	11th to 20th	Day	14% 7% 4 5% 4 3 3 3 4 7% 46%	1890
	21st to end	Day	16% 10% 4 8% 4 3 3 2 4 7% 40%	1753
December	1st to 10th	Day	8% 10% 3 7% 4 3 3 2 4 5% 51%	2690
	11th to 20th	Day	13% 8% 5% 9% 5% 4 4 3 5% 6% 38%	3088
	21st to end	Day	22% 17% 5% 10% 5% 4 4 3 4 4 22%	4070
January	1st to 10th	Night	15% 11% 7% 11% 5% 4 4 3 4 5% 32%	6488
	11th to 20th	Night	11% 10% 5% 12% 6% 5% 5% 4 4 4 34%	6096
	21st to end	Night	17% 14% 4 8% 4 4 3 3 4 5% 34%	6490
February	1st to 10th	Night	15% 11% 5% 8% 5% 5% 4 3 4 5% 35%	2600
	11th to 20th	Night	16% 8% 4 7% 4 5% 4 3 5% 6% 39%	2397
	21st to end	Night	15% 8% 4 6% 4 3 4 3 4 5% 43%	1980
March	1st to 10th	Night	19% 12% 3 5% 3 3 3 2 3 4 43%	5263
	11th to 20th	Night	12% 8% 2 5% 3 3 3 3 4 7% 50%	4980
	21st to end	Night	17% 10% 3 8% 4 4 4 4 5% 6% 35%	5220
April	1st to 10th	Night	12% 6% 3 7% 5% 3 4 3 4 7% 45%	2000
	11th to 20th	Night	14% 7% 2 5% 4 3 4 3 6% 7% 45%	1975
	21st to end	Night	17% 9% 2 6% 3 4 4 3 4 7% 41%	2000
May	1st to 10th	Night	18% 8% 2 7% 4 4 4 3 5% 9% 35%	4324
	11th to 20th	Night	14% 8% 2 5% 4 4 4 3 6% 8% 42%	3596
	21st to end	Night	14% 6% 2 6% 4 4 5% 3 5% 8% 43%	3942
June	1st to 10th	Night	8% 5% 1 5% 3 4 4 4 6% 9% 51%	1600
	11th to 20th	Night	7% 5% 2 5% 3 4 4 3 6% 8% 53%	1600
	21st to end	Night	5% 3 2 5% 4 4 5% 4 8% 10% 52%	1600
July	1st to 10th	Night	9% 5% 3 7% 4 4 4 4 6% 9% 46%	3618
	11th to 20th	Night	5% 4 2 6% 4 4 5% 4 7% 10% 49%	3617
	21st to end	Night	7% 5% 2 7% 4 4 5% 5% 8% 11% 42%	4345
August	1st to 10th	Night	4 3 1 4 2 4 4 4 5% 8% 60%	2926
	11th to 20th	Night	12% 5% 2 6% 4 3 4 3 4 7% 50%	3156
	21st to end	Night	5% 3 1 4 3 3 4 4 6% 10% 56%	3586
September	1st to 10th	Night	12% 4 2 4 3 3 4 3 4 6% 55%	2000
	11th to 20th	Night	8% 5% 2 5% 3 4 4 3 6% 8% 53%	2000
	21st to end	Night	8% 5% 2 5% 4 3 4 3 5% 7% 55%	2225
October	1st to 10th	Night	7% 4 2 5% 3 2 4 3 5% 6% 59%	2400
	11th to 20th	Night	13% 5% 2 5% 3 3 3 2 5% 7% 53%	2400
	21st to end	Night	18% 8% 2 4 3 3 4 2 4 5% 47%	2640
November	1st to 10th	Night	10% 5% 2 5% 3 3 4 3 5% 5% 54%	2662
	11th to 20th	Night	13% 6% 2 5% 3 3 3 3 5% 6% 50%	2730
	21st to end	Night	18% 9% 3 6% 3 3 3 3 4 6% 42%	2861
December	1st to 10th	Night	11% 9% 3 7% 5% 3 4 3 4 5% 46%	4720
	11th to 20th	Night	15% 9% 4 6% 4 3 4 3 5% 6% 41%	5339
	21st to end	Night	24% 19% 4 9% 5% 4 4 3 3 4 22%	7150

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% 1 9% 21% 10% 1	3698
	11th to 20th	Day	45% 2 12% 21% 15% 5%	4011
	21st to end	Day	55% 1 8% 16% 17% 3	4488
February	1st to 10th	Day	52% 3 12% 22% 11% 1	1800
	11th to 20th	Day	48% 3 11% 21% 16% 3	1897
	21st to end	Day	47% 2 8% 25% 15% 4	1650
March	1st to 10th	Day	41% 1 5% 24% 25% 3	4632
	11th to 20th	Day	33% 2 9% 27% 24% 5%	4980
	21st to end	Day	49% 2 14% 27% 8% 1	5710
April	1st to 10th	Day	44% 3 10% 26% 17% 1	2400
	11th to 20th	Day	45% 3 9% 26% 15% 3	2374
	21st to end	Day	46% 3 12% 24% 14% 1	2400
May	1st to 10th	Day	49% 2 12% 23% 13%	5607
	11th to 20th	Day	45% 3 10% 26% 14% 2	6323
	21st to end	Day	43% 3 8% 26% 19% 1	6949
June	1st to 10th	Day	32% 4 14% 32% 16% 2	2800
	11th to 20th	Day	31% 4 12% 28% 21% 3	2800
	21st to end	Day	29% 5% 18% 26% 17% 4	2800
July	1st to 10th	Day	35% 3 11% 30% 19% 2	6291
	11th to 20th	Day	38% 4 15% 27% 15% 1	6285
	21st to end	Day	37% 4 19% 30% 10% 1	6337
August	1st to 10th	Day	29% 4 14% 39% 14% 1	4220
	11th to 20th	Day	39% 4 12% 28% 16% 1	3930
	21st to end	Day	30% 3 15% 34% 15% 3	4311
September	1st to 10th	Day	33% 3 9% 28% 22% 5%	2400
	11th to 20th	Day	31% 3 9% 30% 24% 4	2398
	21st to end	Day	31% 4 8% 28% 25% 3	2150
October	1st to 10th	Day	19% 2 5% 20% 47% 7%	3260
	11th to 20th	Day	24% 1 6% 22% 38% 8%	3240
	21st to end	Day	36% 1 7% 28% 26% 2	3538
November	1st to 10th	Day	32% 2 12% 28% 21% 4	1854
	11th to 20th	Day	40% 2 8% 27% 20% 5%	1890
	21st to end	Day	47% 2 9% 26% 15%	1753
December	1st to 10th	Day	38% 2 14% 30% 16%	2690
	11th to 20th	Day	47% 2 11% 26% 13% 2	3085
	21st to end	Day	68% 2 11% 13% 6% 1	4070
January	1st to 10th	Night	56% 1 10% 24% 8% 1	6488
	11th to 20th	Night	54% 2 7% 22% 13% 2	6096
	21st to end	Night	54% 1 8% 20% 15% 2	6490
February	1st to 10th	Night	53% 2 10% 21% 12% 2	2600
	11th to 20th	Night	48% 3 9% 22% 17% 3	2398
	21st to end	Night	44% 2 11% 25% 16% 3	1980
March	1st to 10th	Night	47% 1 5% 23% 21% 2	5263
	11th to 20th	Night	36% 2 8% 25% 23% 6%	4980
	21st to end	Night	50% 2 10% 26% 10% 1	5220
April	1st to 10th	Night	40% 3 9% 26% 19% 4	2000
	11th to 20th	Night	39% 2 9% 25% 20% 4	1975
	21st to end	Night	44% 3 9% 25% 17% 2	2000
May	1st to 10th	Night	47% 3 15% 20% 13% 1	4354
	11th to 20th	Night	42% 3 12% 26% 14% 4	3597
	21st to end	Night	41% 3 11% 25% 19% 1	3950
June	1st to 10th	Night	30% 3 15% 29% 19% 3	1600
	11th to 20th	Night	29% 4 11% 28% 25% 4	1600
	21st to end	Night	26% 4 16% 29% 20% 7%	1600
July	1st to 10th	Night	36% 3 9% 33% 17% 2	3580
	11th to 20th	Night	31% 5% 15% 32% 16% 2	3572
	21st to end	Night	36% 4 19% 29% 11% 1	4219
August	1st to 10th	Night	23% 3 16% 38% 19% 1	2916
	11th to 20th	Night	35% 3 11% 28% 20% 2	3186
	21st to end	Night	24% 3 17% 34% 18% 3	3586
September	1st to 10th	Night	32% 2 9% 26% 25% 6%	2000
	11th to 20th	Night	30% 3 8% 27% 26% 5%	2000
	21st to end	Night	30% 3 8% 26% 28% 5%	2225
October	1st to 10th	Night	18% 2 6% 21% 47% 7%	3920
	11th to 20th	Night	23% 2 7% 24% 36% 8%	3899
	21st to end	Night	33% 2 7% 27% 26% 5%	4252
November	1st to 10th	Night	33% 2 11% 27% 21% 6%	2662
	11th to 20th	Night	36% 2 7% 29% 22% 4	2730
	21st to end	Night	45% 2 10% 25% 16% 2	2861
December	1st to 10th	Night	42% 2 9% 33% 14% 1	4720
	11th to 20th	Night	44% 2 11% 25% 17% 1	5341
	21st to end	Night	68% 2 11% 13% 5% 1	7150

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	17% 19% 35% 24% 5%	330
	11th to 20th	Day	24% 19% 36% 19% 3	318
	21st to end	Day	16% 15% 44% 21% 4	330
February	1st to 10th	Day	25% 12% 40% 19% 4	300
	11th to 20th	Day	24% 15% 37% 17% 7% 1	300
	21st to end	Day	24% 13% 40% 18% 4	249
March	1st to 10th	Day	18% 14% 44% 21% 3	300
	11th to 20th	Day	27% 14% 31% 21% 5% 1	300
	21st to end	Day	29% 12% 36% 16% 6%	434
April	1st to 10th	Day	19% 11% 36% 23% 10% 1	500
	11th to 20th	Day	22% 14% 29% 22% 12% 1	492
	21st to end	Day	20% 11% 32% 27% 8% 1	500
May	1st to 10th	Day	15% 11% 30% 30% 12% 2	531
	11th to 20th	Day	18% 9% 23% 29% 17% 4	725
	21st to end	Day	14% 7% 26% 29% 15% 9%	789
June	1st to 10th	Day	9% 5% 16% 31% 28% 11%	730
	11th to 20th	Day	9% 2 16% 35% 30% 7%	730
	21st to end	Day	5% 4 24% 38% 23% 7%	730
July	1st to 10th	Day	10% 2 9% 28% 34% 16%	721
	11th to 20th	Day	6% 3 15% 36% 31% 9%	718
	21st to end	Day	8% 2 12% 32% 35% 11%	794
August	1st to 10th	Day	9% 2 11% 36% 32% 10%	726
	11th to 20th	Day	12% 3 14% 27% 33% 12%	552
	21st to end	Day	8% 2 11% 29% 37% 14%	583
September	1st to 10th	Day	12% 2 12% 31% 30% 12%	530
	11th to 20th	Day	7% 2 11% 29% 33% 17%	530
	21st to end	Day	9% 5% 21% 30% 23% 12%	480
October	1st to 10th	Day	11% 5% 23% 32% 19% 9%	330
	11th to 20th	Day	14% 16% 30% 24% 12% 3	330
	21st to end	Day	25% 17% 28% 22% 8%	363
November	1st to 10th	Day	15% 9% 33% 27% 11% 4	330
	11th to 20th	Day	16% 18% 32% 20% 12% 2	330
	21st to end	Day	25% 12% 28% 23% 10% 1	330
December	1st to 10th	Day	13% 15% 37% 24% 7% 3	330
	11th to 20th	Day	20% 13% 35% 26% 7%	330
	21st to end	Day	26% 16% 37% 17% 5%	363
January	1st to 10th	Night	18% 13% 36% 28% 6%	1050
	11th to 20th	Night	20% 14% 37% 24% 5%	1031
	21st to end	Night	19% 12% 38% 28% 3	1100
February	1st to 10th	Night	22% 11% 37% 28% 3	1000
	11th to 20th	Night	21% 13% 36% 27% 3	842
	21st to end	Night	21% 12% 41% 24% 2	660
March	1st to 10th	Night	20% 12% 38% 26% 4	755
	11th to 20th	Night	20% 10% 33% 29% 8%	600
	21st to end	Night	26% 9% 30% 29% 5%	660
April	1st to 10th	Night	16% 12% 35% 31% 5%	600
	11th to 20th	Night	17% 7% 35% 32% 9%	593
	21st to end	Night	19% 7% 38% 29% 7%	600
May	1st to 10th	Night	17% 6% 27% 39% 10% 1	600
	11th to 20th	Night	17% 5% 25% 34% 18% 1	591
	21st to end	Night	13% 2 19% 43% 20% 2	650
June	1st to 10th	Night	9% 2 18% 41% 28% 2	600
	11th to 20th	Night	9% 2 16% 47% 25% 2	600
	21st to end	Night	5% 2 18% 48% 26% 2	600
July	1st to 10th	Night	11% 2 7% 36% 39% 5%	585
	11th to 20th	Night	6% 2 10% 41% 38% 2	582
	21st to end	Night	8% 2 8% 41% 38% 3	657
August	1st to 10th	Night	8% 2 7% 43% 39% 3	597
	11th to 20th	Night	7% 2 10% 40% 37% 4	594
	21st to end	Night	6% 2 9% 38% 41% 5%	660
September	1st to 10th	Night	13% 3 12% 37% 31% 6%	600
	11th to 20th	Night	10% 2 10% 36% 38% 5%	600
	21st to end	Night	10% 5% 20% 33% 28% 5%	780
October	1st to 10th	Night	9% 3 22% 38% 25% 4	800
	11th to 20th	Night	16% 7% 30% 32% 15% 1	800
	21st to end	Night	22% 9% 32% 30% 7%	880
November	1st to 10th	Night	13% 7% 34% 36% 10%	820
	11th to 20th	Night	17% 11% 34% 31% 8%	840
	21st to end	Night	22% 10% 33% 28% 6%	971
December	1st to 10th	Night	20% 10% 35% 29% 5% 1	1050
	11th to 20th	Night	22% 9% 31% 32% 6%	1050
	21st to end	Night	27% 11% 33% 26% 3	1155

Page generated at 2026-01-14 00:14:28. Version ac07

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