Green River State Wildlife Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Green River State Wildlife Area clear sky chart from 2005-11-06 to 2026-10-14.

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 4 4 6% 7% 38%	149752
	Night	13% 9% 3 8% 5% 4 4 3 5% 6% 39%	142360
Transparency	Day	44% 4 12% 25% 14% 2	153259
	Night	45% 4 11% 24% 15% 2	146930
Seeing	Day	16% 10% 28% 26% 15% 5%	18523
	Night	17% 9% 31% 31% 11% 1	28269

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	9% 12% 6% 15% 7% 6% 6% 4 6% 6% 23%	4691
	11th to 20th	Day	7% 10% 5% 12% 6% 6% 6% 5% 7% 6% 29%	4710
	21st to end	Day	11% 14% 6% 9% 6% 6% 4 4 5% 6% 29%	5607
February	1st to 10th	Day	13% 15% 4 11% 6% 4 5% 3 5% 5% 27%	1890
	11th to 20th	Day	12% 12% 4 9% 5% 5% 4 3 5% 6% 35%	2006
	21st to end	Day	12% 14% 6% 11% 4 5% 4 3 4 6% 32%	1730
March	1st to 10th	Day	18% 11% 4 6% 4 3 3 2 3 5% 43%	4580
	11th to 20th	Day	10% 7% 3 6% 4 4 4 4 6% 7% 44%	4944
	21st to end	Day	20% 11% 4 11% 5% 5% 4 3 5% 6% 26%	6005
April	1st to 10th	Day	17% 14% 3 7% 5% 4 4 3 5% 6% 32%	2520
	11th to 20th	Day	17% 9% 3 7% 5% 4 4 3 5% 6% 35%	2494
	21st to end	Day	20% 9% 2 7% 4 5% 4 4 4 7% 34%	2541
May	1st to 10th	Day	14% 7% 3 7% 5% 4 5% 4 5% 8% 39%	7727
	11th to 20th	Day	13% 6% 2 7% 5% 5% 5% 4 5% 8% 42%	8222
	21st to end	Day	12% 7% 2 7% 5% 4 5% 4 6% 9% 37%	9047
June	1st to 10th	Day	10% 5% 2 5% 5% 5% 4 4 7% 8% 45%	2940
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 46%	2940
	21st to end	Day	11% 5% 2 6% 5% 4 5% 5% 7% 9% 39%	2940
July	1st to 10th	Day	8% 6% 3 7% 5% 5% 5% 5% 7% 9% 41%	8280
	11th to 20th	Day	8% 4 2 5% 4 4 5% 4 6% 9% 49%	8280
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 4 7% 9% 40%	8990
August	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 7% 10% 41%	6227
	11th to 20th	Day	14% 7% 2 7% 4 4 4 4 6% 9% 37%	5536
	21st to end	Day	7% 5% 2 5% 4 4 4 4 5% 9% 51%	6080
September	1st to 10th	Day	12% 5% 1 6% 4 3 4 3 5% 9% 48%	2520
	11th to 20th	Day	13% 4 1 5% 3 3 4 3 5% 6% 54%	2452
	21st to end	Day	10% 6% 2 6% 4 4 4 4 5% 8% 46%	2310
October	1st to 10th	Day	13% 6% 2 5% 3 3 3 4 5% 6% 50%	2147
	11th to 20th	Day	16% 8% 3 7% 4 4 4 3 4 6% 41%	2030
	21st to end	Day	19% 10% 2 6% 4 3 3 3 4 6% 40%	2049
November	1st to 10th	Day	11% 9% 3 5% 4 4 4 4 5% 8% 45%	1852
	11th to 20th	Day	16% 12% 4 8% 4 4 5% 4 4 6% 33%	1890
	21st to end	Day	16% 13% 5% 8% 5% 4 3 2 4 5% 35%	1727
December	1st to 10th	Day	8% 10% 4 8% 4 4 4 3 4 6% 45%	2690
	11th to 20th	Day	13% 16% 5% 12% 6% 6% 5% 4 5% 4 23%	3088
	21st to end	Day	23% 20% 9% 13% 6% 3 3 3 3 4 13%	4070
January	1st to 10th	Night	11% 13% 5% 13% 5% 5% 3 3 4 5% 33%	8232
	11th to 20th	Night	9% 13% 6% 14% 7% 6% 5% 4 6% 5% 25%	8280
	21st to end	Night	12% 14% 5% 9% 5% 4 4 3 5% 5% 34%	8605
February	1st to 10th	Night	14% 13% 5% 9% 5% 4 4 3 4 5% 34%	2730
	11th to 20th	Night	12% 11% 3 8% 4 4 4 4 4 7% 39%	2500
	21st to end	Night	16% 11% 4 10% 4 3 3 3 3 5% 38%	2076
March	1st to 10th	Night	17% 10% 3 5% 4 4 4 3 4 5% 41%	5493
	11th to 20th	Night	10% 6% 3 6% 5% 4 4 3 5% 7% 47%	5278
	21st to end	Night	18% 12% 5% 10% 5% 5% 5% 3 5% 5% 27%	5166
April	1st to 10th	Night	17% 12% 3 6% 3 5% 3 3 4 6% 37%	2100
	11th to 20th	Night	19% 9% 2 6% 3 4 4 3 4 6% 41%	2075
	21st to end	Night	15% 8% 3 8% 5% 4 4 4 6% 7% 36%	2077
May	1st to 10th	Night	15% 8% 3 7% 5% 4 4 4 6% 7% 38%	5128
	11th to 20th	Night	10% 5% 2 7% 4 5% 5% 4 7% 9% 42%	4670
	21st to end	Night	13% 7% 2 7% 4 4 4 4 5% 8% 40%	5139
June	1st to 10th	Night	9% 5% 2 6% 5% 4 4 4 5% 8% 48%	1680
	11th to 20th	Night	9% 4 2 6% 4 4 4 4 7% 10% 46%	1680
	21st to end	Night	10% 5% 2 5% 5% 5% 5% 4 6% 7% 45%	1680
July	1st to 10th	Night	10% 5% 2 7% 4 4 4 4 6% 9% 45%	4708
	11th to 20th	Night	7% 5% 2 5% 3 3 4 3 5% 7% 55%	4707
	21st to end	Night	8% 5% 2 6% 4 5% 5% 4 6% 8% 46%	5117
August	1st to 10th	Night	11% 5% 2 6% 4 4 4 4 5% 8% 47%	3939
	11th to 20th	Night	11% 6% 3 7% 4 4 4 4 5% 8% 43%	4511
	21st to end	Night	6% 4 2 5% 4 4 4 3 6% 9% 55%	5046
September	1st to 10th	Night	9% 4 2 4 3 3 3 3 5% 7% 58%	2100
	11th to 20th	Night	10% 4 2 4 3 4 4 4 5% 7% 52%	2146
	21st to end	Night	10% 5% 2 6% 4 4 4 4 6% 7% 48%	2310
October	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 4 5% 55%	2467
	11th to 20th	Night	16% 7% 3 6% 4 3 3 3 4 5% 46%	2437
	21st to end	Night	19% 10% 2 6% 4 4 4 3 4 6% 38%	2790
November	1st to 10th	Night	11% 8% 2 5% 3 3 3 3 5% 5% 51%	2666
	11th to 20th	Night	15% 10% 4 8% 4 4 4 3 5% 6% 38%	2730
	21st to end	Night	16% 12% 3 8% 5% 4 3 2 4 6% 37%	2888
December	1st to 10th	Night	10% 9% 3 8% 5% 4 5% 4 5% 6% 42%	4720
	11th to 20th	Night	15% 15% 5% 9% 4 4 4 3 4 5% 32%	5339
	21st to end	Night	22% 19% 6% 12% 6% 5% 4 3 4 5% 15%	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	61% 4 13% 16% 6%	4692
	11th to 20th	Day	54% 4 9% 18% 13% 3	4710
	21st to end	Day	56% 3 13% 20% 7%	5607
February	1st to 10th	Day	58% 2 12% 18% 8% 1	1890
	11th to 20th	Day	51% 3 11% 24% 9% 2	2016
	21st to end	Day	54% 3 11% 21% 10% 1	1730
March	1st to 10th	Day	47% 2 9% 27% 12% 3	4580
	11th to 20th	Day	39% 2 11% 34% 13% 1	4944
	21st to end	Day	60% 3 12% 18% 6% 1	6007
April	1st to 10th	Day	53% 3 11% 23% 10%	2520
	11th to 20th	Day	49% 3 11% 24% 12% 2	2494
	21st to end	Day	50% 4 10% 21% 12% 2	2541
May	1st to 10th	Day	44% 4 9% 24% 18% 1	7762
	11th to 20th	Day	41% 5% 10% 27% 15% 2	8226
	21st to end	Day	43% 4 11% 23% 15% 4	9061
June	1st to 10th	Day	36% 4 14% 29% 17% 2	2940
	11th to 20th	Day	34% 4 11% 25% 22% 3	2940
	21st to end	Day	39% 6% 13% 26% 14% 2	2940
July	1st to 10th	Day	37% 7% 14% 26% 15% 1	8211
	11th to 20th	Day	31% 6% 14% 32% 17% 1	8205
	21st to end	Day	38% 7% 16% 24% 14% 1	8794
August	1st to 10th	Day	37% 6% 14% 29% 13% 1	6212
	11th to 20th	Day	42% 7% 14% 25% 12% 1	5572
	21st to end	Day	30% 5% 13% 34% 17% 2	6079
September	1st to 10th	Day	34% 4 10% 28% 20% 4	2520
	11th to 20th	Day	32% 4 10% 30% 21% 3	2452
	21st to end	Day	36% 4 10% 28% 21% 2	2310
October	1st to 10th	Day	24% 3 6% 31% 36% 1	3433
	11th to 20th	Day	31% 2 10% 25% 29% 3	3270
	21st to end	Day	42% 2 9% 27% 16% 3	3287
November	1st to 10th	Day	38% 3 14% 28% 14% 3	1852
	11th to 20th	Day	53% 2 11% 23% 10% 1	1890
	21st to end	Day	54% 3 13% 22% 8%	1727
December	1st to 10th	Day	42% 3 14% 32% 8% 1	2690
	11th to 20th	Day	63% 4 11% 15% 6% 1	3085
	21st to end	Day	78% 3 7% 7% 5%	4070
January	1st to 10th	Night	55% 2 14% 20% 8%	8233
	11th to 20th	Night	60% 3 11% 12% 14% 1	8280
	21st to end	Night	52% 3 12% 22% 11% 1	8605
February	1st to 10th	Night	54% 3 10% 20% 12% 1	2730
	11th to 20th	Night	47% 3 10% 25% 13% 1	2501
	21st to end	Night	51% 3 10% 21% 13% 3	2076
March	1st to 10th	Night	47% 2 10% 24% 13% 4	5493
	11th to 20th	Night	38% 2 10% 30% 16% 4	5278
	21st to end	Night	60% 3 10% 19% 8% 1	5166
April	1st to 10th	Night	49% 2 10% 23% 14% 2	2100
	11th to 20th	Night	46% 3 7% 23% 17% 4	2075
	21st to end	Night	47% 4 10% 25% 11% 3	2077
May	1st to 10th	Night	46% 4 9% 21% 19% 2	5155
	11th to 20th	Night	38% 4 14% 25% 16% 4	4671
	21st to end	Night	42% 4 9% 23% 18% 4	5149
June	1st to 10th	Night	34% 4 13% 27% 19% 3	1680
	11th to 20th	Night	33% 4 11% 25% 24% 3	1680
	21st to end	Night	37% 5% 14% 23% 17% 3	1680
July	1st to 10th	Night	35% 6% 16% 25% 17% 2	4670
	11th to 20th	Night	28% 6% 11% 30% 24% 2	4662
	21st to end	Night	33% 8% 14% 26% 16% 3	5002
August	1st to 10th	Night	35% 6% 14% 27% 17% 1	3930
	11th to 20th	Night	38% 8% 15% 26% 12% 1	4541
	21st to end	Night	26% 5% 13% 35% 18% 2	5046
September	1st to 10th	Night	29% 3 10% 29% 26% 3	2100
	11th to 20th	Night	31% 3 9% 31% 22% 3	2146
	21st to end	Night	34% 5% 9% 28% 21% 3	2310
October	1st to 10th	Night	24% 2 6% 34% 32% 3	3961
	11th to 20th	Night	32% 3 7% 22% 32% 4	3936
	21st to end	Night	42% 3 9% 24% 19% 3	4502
November	1st to 10th	Night	35% 4 11% 28% 18% 3	2666
	11th to 20th	Night	47% 3 10% 25% 13% 2	2730
	21st to end	Night	50% 3 10% 25% 12% 1	2888
December	1st to 10th	Night	42% 4 13% 30% 9% 1	4720
	11th to 20th	Night	56% 3 12% 20% 9% 1	5341
	21st to end	Night	74% 3 7% 11% 4	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	19% 12% 35% 25% 8% 1	330
	11th to 20th	Day	17% 16% 44% 17% 5% 1	330
	21st to end	Day	20% 15% 37% 22% 4 1	363
February	1st to 10th	Day	19% 17% 35% 23% 5% 1	330
	11th to 20th	Day	21% 18% 34% 22% 5%	330
	21st to end	Day	20% 19% 44% 14% 2	273
March	1st to 10th	Day	23% 18% 35% 18% 6%	330
	11th to 20th	Day	24% 18% 33% 18% 6% 1	330
	21st to end	Day	25% 15% 35% 19% 5% 1	552
April	1st to 10th	Day	26% 16% 30% 21% 5% 1	540
	11th to 20th	Day	20% 21% 28% 20% 8% 2	532
	21st to end	Day	23% 14% 31% 20% 10% 2	540
May	1st to 10th	Day	17% 14% 32% 26% 9% 2	577
	11th to 20th	Day	19% 12% 27% 25% 14% 3	775
	21st to end	Day	14% 9% 29% 24% 16% 8%	844
June	1st to 10th	Day	11% 6% 28% 32% 19% 5%	780
	11th to 20th	Day	10% 6% 30% 33% 16% 5%	780
	21st to end	Day	13% 7% 31% 30% 14% 5%	780
July	1st to 10th	Day	10% 3 15% 31% 25% 16%	771
	11th to 20th	Day	11% 3 21% 31% 24% 11%	768
	21st to end	Day	7% 4 19% 35% 28% 7%	849
August	1st to 10th	Day	7% 3 19% 33% 28% 10%	776
	11th to 20th	Day	11% 6% 16% 29% 24% 15%	584
	21st to end	Day	7% 4 18% 33% 28% 10%	627
September	1st to 10th	Day	13% 5% 19% 33% 22% 7%	570
	11th to 20th	Day	11% 2 19% 31% 26% 11%	570
	21st to end	Day	12% 9% 25% 26% 21% 6%	570
October	1st to 10th	Day	15% 6% 26% 31% 18% 4	407
	11th to 20th	Day	16% 19% 35% 18% 11% 1	339
	21st to end	Day	31% 12% 28% 23% 5% 1	363
November	1st to 10th	Day	15% 15% 36% 22% 9% 3	330
	11th to 20th	Day	23% 19% 31% 18% 8% 2	330
	21st to end	Day	25% 13% 34% 21% 7%	330
December	1st to 10th	Day	17% 15% 39% 22% 6% 2	330
	11th to 20th	Day	18% 12% 39% 24% 7%	330
	21st to end	Day	27% 19% 34% 17% 3	363
January	1st to 10th	Night	19% 12% 39% 24% 6%	1050
	11th to 20th	Night	18% 15% 38% 23% 6%	1050
	21st to end	Night	20% 12% 36% 28% 4	1155
February	1st to 10th	Night	22% 12% 37% 25% 4	1050
	11th to 20th	Night	19% 11% 38% 28% 5%	865
	21st to end	Night	20% 14% 39% 23% 4	692
March	1st to 10th	Night	22% 11% 38% 24% 5%	840
	11th to 20th	Night	18% 11% 33% 32% 6%	714
	21st to end	Night	23% 12% 37% 22% 6% 1	693
April	1st to 10th	Night	23% 15% 34% 22% 5%	630
	11th to 20th	Night	22% 13% 33% 25% 6%	623
	21st to end	Night	18% 13% 30% 32% 7%	630
May	1st to 10th	Night	18% 9% 33% 32% 8% 1	630
	11th to 20th	Night	18% 5% 33% 33% 10%	621
	21st to end	Night	15% 6% 28% 36% 14% 1	683
June	1st to 10th	Night	9% 5% 25% 49% 12% 1	630
	11th to 20th	Night	9% 5% 30% 41% 14% 1	630
	21st to end	Night	11% 4 28% 41% 16%	630
July	1st to 10th	Night	9% 1 14% 42% 29% 5%	615
	11th to 20th	Night	8% 2 18% 42% 27% 3	612
	21st to end	Night	6% 2 17% 46% 28% 2	690
August	1st to 10th	Night	7% 2 15% 42% 31% 4	627
	11th to 20th	Night	9% 3 13% 42% 29% 5%	624
	21st to end	Night	9% 1 16% 43% 30% 2	693
September	1st to 10th	Night	11% 3 18% 39% 26% 3	630
	11th to 20th	Night	10% 4 21% 36% 25% 4	676
	21st to end	Night	11% 7% 25% 35% 19% 2	840
October	1st to 10th	Night	12% 7% 29% 34% 17% 2	840
	11th to 20th	Night	19% 11% 31% 27% 11%	813
	21st to end	Night	25% 11% 32% 25% 7%	880
November	1st to 10th	Night	16% 7% 41% 26% 9% 1	820
	11th to 20th	Night	19% 13% 38% 24% 5%	840
	21st to end	Night	23% 13% 33% 25% 6%	998
December	1st to 10th	Night	21% 12% 37% 24% 5%	1050
	11th to 20th	Night	23% 11% 35% 25% 5%	1050
	21st to end	Night	28% 13% 34% 22% 2	1155

Page generated at 2026-10-11 04:06:26. Version ac07

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