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 2025-06-10.

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	13% 9% 3 8% 5% 4 4 4 5% 7% 38%	119678
	Night	13% 10% 3 8% 5% 4 4 3 5% 6% 39%	118785
Transparency	Day	45% 4 11% 24% 14% 2	123230
	Night	46% 3 11% 23% 15% 2	123374
Seeing	Day	16% 10% 28% 26% 15% 5%	16584
	Night	17% 9% 31% 30% 11% 1	26513

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% 7% 16% 7% 6% 6% 4 5% 5% 24%	3617
	11th to 20th	Day	9% 10% 6% 12% 6% 6% 5% 5% 8% 5% 28%	3620
	21st to end	Day	13% 16% 7% 10% 5% 4 4 3 4 6% 28%	4325
February	1st to 10th	Day	14% 15% 4 11% 6% 5% 5% 3 5% 5% 27%	1800
	11th to 20th	Day	13% 11% 4 9% 5% 5% 4 3 5% 7% 35%	1908
	21st to end	Day	13% 14% 6% 10% 4 5% 4 3 4 6% 31%	1650
March	1st to 10th	Day	17% 11% 4 6% 4 3 3 2 3 5% 43%	4480
	11th to 20th	Day	10% 7% 3 6% 4 4 4 4 6% 7% 45%	4837
	21st to end	Day	20% 12% 5% 11% 5% 5% 4 3 5% 6% 25%	5875
April	1st to 10th	Day	17% 13% 3 7% 5% 4 4 3 5% 6% 33%	2400
	11th to 20th	Day	17% 9% 3 7% 5% 4 4 3 5% 6% 36%	2374
	21st to end	Day	20% 9% 2 7% 5% 5% 4 4 4 6% 34%	2420
May	1st to 10th	Day	16% 7% 3 7% 5% 4 5% 4 5% 8% 37%	5946
	11th to 20th	Day	14% 5% 2 7% 4 5% 4 3 5% 7% 43%	6319
	21st to end	Day	13% 7% 2 7% 5% 4 5% 4 6% 9% 38%	6935
June	1st to 10th	Day	10% 5% 2 6% 5% 4 4 4 7% 8% 46%	2787
	11th to 20th	Day	10% 4 2 6% 4 4 5% 4 6% 9% 46%	2660
	21st to end	Day	12% 6% 2 6% 5% 4 6% 5% 7% 9% 38%	2660
July	1st to 10th	Day	10% 8% 3 8% 5% 5% 6% 5% 7% 8% 35%	4440
	11th to 20th	Day	7% 4 1 5% 3 3 4 4 6% 9% 52%	4440
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 4 7% 10% 40%	4813
August	1st to 10th	Day	8% 4 2 6% 5% 4 5% 4 7% 10% 43%	4243
	11th to 20th	Day	11% 5% 2 5% 3 4 4 4 7% 10% 43%	3764
	21st to end	Day	8% 6% 2 5% 4 4 4 4 5% 9% 50%	4180
September	1st to 10th	Day	12% 5% 1 6% 4 3 4 3 5% 9% 47%	2280
	11th to 20th	Day	13% 3 1 4 3 3 3 3 5% 7% 55%	2218
	21st to end	Day	10% 7% 2 6% 4 4 4 4 5% 8% 47%	2090
October	1st to 10th	Day	13% 6% 2 5% 3 3 3 3 5% 6% 49%	1943
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 3 5% 6% 40%	1900
	21st to end	Day	19% 10% 2 6% 4 3 3 3 4 5% 40%	1947
November	1st to 10th	Day	11% 9% 2 5% 4 4 4 4 5% 8% 44%	1762
	11th to 20th	Day	16% 12% 4 8% 5% 4 5% 4 4 6% 33%	1800
	21st to end	Day	16% 13% 5% 8% 5% 4 3 2 4 5% 35%	1645
December	1st to 10th	Day	8% 10% 3 8% 4 4 4 3 4 7% 46%	2610
	11th to 20th	Day	13% 16% 5% 12% 6% 6% 5% 4 5% 4 23%	3008
	21st to end	Day	22% 20% 9% 14% 6% 3 3 3 3 4 13%	3982
January	1st to 10th	Night	11% 13% 6% 13% 6% 5% 4 3 4 4 32%	6348
	11th to 20th	Night	11% 15% 6% 13% 7% 6% 4 4 6% 5% 23%	6360
	21st to end	Night	15% 15% 6% 9% 5% 3 4 3 4 4 32%	6651
February	1st to 10th	Night	15% 13% 5% 9% 5% 4 4 4 4 5% 33%	2600
	11th to 20th	Night	13% 11% 3 8% 4 4 4 4 4 7% 38%	2378
	21st to end	Night	16% 12% 4 9% 4 3 3 3 3 6% 38%	1980
March	1st to 10th	Night	17% 10% 3 5% 4 4 4 3 4 5% 41%	5373
	11th to 20th	Night	10% 6% 3 6% 5% 4 4 3 5% 7% 48%	5164
	21st to end	Night	18% 12% 5% 10% 5% 5% 5% 3 4 5% 27%	5054
April	1st to 10th	Night	17% 11% 2 5% 3 5% 3 3 4 6% 39%	2000
	11th to 20th	Night	19% 9% 2 6% 4 4 4 3 4 5% 41%	1975
	21st to end	Night	15% 8% 3 8% 5% 4 3 4 6% 7% 35%	1978
May	1st to 10th	Night	17% 9% 3 7% 5% 4 4 4 5% 7% 35%	3949
	11th to 20th	Night	11% 5% 2 7% 4 4 5% 4 7% 9% 42%	3596
	21st to end	Night	14% 7% 2 6% 4 4 4 4 5% 8% 41%	3942
June	1st to 10th	Night	9% 5% 2 6% 4 4 5% 5% 5% 8% 49%	1597
	11th to 20th	Night	9% 3 2 6% 4 3 5% 4 8% 9% 47%	1520
	21st to end	Night	9% 5% 2 5% 5% 5% 5% 5% 6% 7% 45%	1520
July	1st to 10th	Night	15% 6% 3 7% 4 5% 4 4 6% 7% 40%	2530
	11th to 20th	Night	6% 4 1 5% 3 4 4 3 6% 7% 58%	2530
	21st to end	Night	5% 4 2 7% 5% 5% 5% 5% 8% 8% 47%	2750
August	1st to 10th	Night	6% 4 2 4 4 4 4 4 6% 9% 53%	2694
	11th to 20th	Night	8% 5% 2 6% 4 4 4 3 5% 8% 52%	3065
	21st to end	Night	7% 4 2 5% 3 4 4 3 6% 9% 53%	3476
September	1st to 10th	Night	10% 5% 2 4 3 2 3 3 4 6% 58%	1900
	11th to 20th	Night	10% 4 2 4 4 4 4 4 5% 7% 53%	1942
	21st to end	Night	9% 5% 2 7% 3 4 4 4 6% 7% 48%	2090
October	1st to 10th	Night	11% 5% 2 6% 4 3 3 3 4 5% 54%	2232
	11th to 20th	Night	16% 7% 3 6% 4 3 3 2 4 5% 47%	2280
	21st to end	Night	19% 10% 2 6% 3 4 4 3 5% 6% 37%	2650
November	1st to 10th	Night	11% 8% 2 4 3 3 3 3 5% 5% 51%	2536
	11th to 20th	Night	15% 9% 4 8% 4 4 4 3 5% 6% 37%	2600
	21st to end	Night	16% 11% 3 7% 5% 4 3 2 4 6% 38%	2750
December	1st to 10th	Night	10% 9% 3 7% 5% 4 5% 4 5% 6% 42%	4580
	11th to 20th	Night	16% 16% 5% 9% 4 4 4 3 4 5% 32%	5199
	21st to end	Night	22% 19% 6% 12% 6% 5% 4 3 4 5% 15%	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	61% 3 11% 17% 7%	3618
	11th to 20th	Day	56% 3 10% 12% 16% 4	3620
	21st to end	Day	59% 2 12% 18% 8%	4325
February	1st to 10th	Day	58% 2 12% 18% 8% 1	1800
	11th to 20th	Day	52% 3 10% 24% 10% 2	1918
	21st to end	Day	54% 3 10% 21% 10% 2	1650
March	1st to 10th	Day	47% 2 9% 27% 13% 3	4480
	11th to 20th	Day	39% 2 11% 34% 13% 1	4837
	21st to end	Day	61% 3 12% 17% 6% 1	5877
April	1st to 10th	Day	52% 3 11% 23% 10%	2400
	11th to 20th	Day	48% 2 10% 25% 12% 2	2374
	21st to end	Day	51% 4 10% 21% 12% 2	2420
May	1st to 10th	Day	47% 4 10% 23% 16% 1	5981
	11th to 20th	Day	42% 5% 9% 29% 14% 2	6323
	21st to end	Day	42% 4 12% 26% 13% 3	6949
June	1st to 10th	Day	35% 3 14% 29% 17% 2	2787
	11th to 20th	Day	34% 4 11% 25% 23% 3	2660
	21st to end	Day	40% 6% 13% 25% 14% 2	2660
July	1st to 10th	Day	43% 6% 12% 25% 11% 2	4371
	11th to 20th	Day	27% 5% 17% 32% 17% 2	4365
	21st to end	Day	37% 7% 16% 19% 19% 2	4662
August	1st to 10th	Day	34% 6% 16% 30% 13% 1	4228
	11th to 20th	Day	34% 6% 14% 29% 16% 1	3800
	21st to end	Day	32% 5% 11% 33% 17% 2	4179
September	1st to 10th	Day	36% 4 10% 26% 20% 4	2280
	11th to 20th	Day	30% 4 10% 30% 23% 3	2218
	21st to end	Day	35% 4 10% 28% 21% 2	2090
October	1st to 10th	Day	24% 3 6% 31% 36% 1	3229
	11th to 20th	Day	31% 2 10% 25% 29% 3	3140
	21st to end	Day	42% 2 10% 27% 15% 3	3185
November	1st to 10th	Day	39% 3 14% 27% 14% 3	1762
	11th to 20th	Day	53% 2 11% 22% 10% 1	1800
	21st to end	Day	54% 3 13% 22% 8%	1645
December	1st to 10th	Day	41% 3 14% 33% 8% 1	2610
	11th to 20th	Day	64% 4 11% 15% 6% 1	3005
	21st to end	Day	77% 3 8% 7% 5%	3982
January	1st to 10th	Night	56% 2 11% 21% 9%	6348
	11th to 20th	Night	63% 3 10% 10% 14% 1	6360
	21st to end	Night	57% 2 10% 19% 12% 1	6651
February	1st to 10th	Night	54% 3 10% 19% 13% 1	2600
	11th to 20th	Night	47% 3 10% 25% 14% 1	2379
	21st to end	Night	50% 3 10% 21% 13% 3	1980
March	1st to 10th	Night	47% 2 9% 24% 13% 4	5373
	11th to 20th	Night	37% 3 10% 30% 16% 4	5164
	21st to end	Night	60% 3 10% 19% 8% 1	5054
April	1st to 10th	Night	47% 2 10% 24% 14% 2	2000
	11th to 20th	Night	46% 3 7% 24% 16% 4	1975
	21st to end	Night	48% 4 10% 24% 11% 3	1978
May	1st to 10th	Night	50% 3 10% 18% 17% 2	3976
	11th to 20th	Night	39% 4 14% 26% 14% 4	3597
	21st to end	Night	41% 4 10% 27% 16% 2	3950
June	1st to 10th	Night	33% 4 13% 28% 19% 3	1597
	11th to 20th	Night	33% 4 11% 25% 24% 4	1520
	21st to end	Night	37% 5% 15% 22% 18% 3	1520
July	1st to 10th	Night	43% 4 15% 22% 12% 3	2490
	11th to 20th	Night	26% 6% 12% 32% 22% 2	2482
	21st to end	Night	31% 10% 15% 21% 19% 5%	2662
August	1st to 10th	Night	27% 6% 17% 31% 19% 2	2685
	11th to 20th	Night	30% 6% 15% 31% 17% 1	3095
	21st to end	Night	29% 5% 12% 32% 19% 3	3476
September	1st to 10th	Night	29% 3 10% 27% 27% 4	1900
	11th to 20th	Night	30% 3 9% 31% 23% 3	1942
	21st to end	Night	34% 4 9% 29% 21% 3	2090
October	1st to 10th	Night	24% 2 6% 34% 31% 3	3726
	11th to 20th	Night	31% 3 7% 22% 32% 4	3779
	21st to end	Night	42% 3 9% 25% 18% 3	4362
November	1st to 10th	Night	35% 4 11% 28% 19% 3	2536
	11th to 20th	Night	48% 3 10% 24% 13% 2	2600
	21st to end	Night	50% 3 10% 25% 12% 1	2750
December	1st to 10th	Night	42% 4 14% 31% 9% 1	4580
	11th to 20th	Night	56% 3 12% 21% 9%	5201
	21st to end	Night	74% 3 7% 11% 4	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	19% 11% 35% 26% 8% 1	300
	11th to 20th	Day	19% 15% 43% 17% 5% 1	300
	21st to end	Day	22% 14% 36% 22% 5% 2	330
February	1st to 10th	Day	21% 17% 35% 22% 5%	300
	11th to 20th	Day	22% 18% 33% 22% 5%	300
	21st to end	Day	19% 20% 43% 15% 2	249
March	1st to 10th	Day	23% 19% 34% 18% 6%	300
	11th to 20th	Day	24% 18% 32% 18% 6% 1	300
	21st to end	Day	26% 15% 33% 19% 5% 1	510
April	1st to 10th	Day	27% 15% 30% 22% 5% 1	500
	11th to 20th	Day	20% 20% 28% 21% 9% 2	492
	21st to end	Day	24% 14% 32% 19% 10% 2	500
May	1st to 10th	Day	18% 13% 31% 26% 9% 2	535
	11th to 20th	Day	20% 11% 27% 24% 14% 3	725
	21st to end	Day	15% 9% 29% 24% 15% 8%	789
June	1st to 10th	Day	10% 6% 27% 32% 19% 5%	726
	11th to 20th	Day	10% 5% 29% 34% 16% 5%	680
	21st to end	Day	13% 8% 30% 30% 14% 5%	680
July	1st to 10th	Day	11% 3 15% 30% 24% 16%	671
	11th to 20th	Day	11% 3 21% 32% 23% 10%	668
	21st to end	Day	6% 4 17% 35% 30% 8%	739
August	1st to 10th	Day	6% 3 20% 33% 28% 10%	676
	11th to 20th	Day	10% 6% 17% 29% 23% 15%	502
	21st to end	Day	7% 4 18% 31% 30% 10%	539
September	1st to 10th	Day	14% 5% 19% 31% 23% 7%	490
	11th to 20th	Day	11% 2 19% 32% 25% 12%	490
	21st to end	Day	11% 11% 27% 25% 21% 5%	490
October	1st to 10th	Day	16% 7% 26% 29% 18% 4	343
	11th to 20th	Day	17% 19% 35% 16% 12% 1	300
	21st to end	Day	32% 12% 28% 23% 5%	330
November	1st to 10th	Day	16% 14% 36% 23% 9% 3	300
	11th to 20th	Day	22% 19% 32% 18% 8% 2	300
	21st to end	Day	25% 13% 35% 20% 7%	300
December	1st to 10th	Day	17% 15% 38% 22% 5% 2	300
	11th to 20th	Day	17% 12% 39% 24% 7%	300
	21st to end	Day	26% 18% 35% 17% 4	330
January	1st to 10th	Night	19% 12% 39% 24% 6% 1	1000
	11th to 20th	Night	19% 14% 37% 24% 6%	1000
	21st to end	Night	21% 11% 35% 28% 4	1100
February	1st to 10th	Night	22% 12% 37% 25% 4	1000
	11th to 20th	Night	19% 11% 38% 26% 5%	823
	21st to end	Night	20% 13% 39% 22% 4	660
March	1st to 10th	Night	22% 11% 37% 24% 5% 1	800
	11th to 20th	Night	17% 10% 33% 33% 6%	680
	21st to end	Night	24% 11% 37% 22% 6% 1	660
April	1st to 10th	Night	23% 14% 34% 23% 5%	600
	11th to 20th	Night	22% 13% 33% 25% 6%	593
	21st to end	Night	18% 13% 31% 31% 7% 1	600
May	1st to 10th	Night	18% 9% 33% 31% 8% 1	600
	11th to 20th	Night	19% 5% 31% 34% 10%	591
	21st to end	Night	15% 6% 28% 35% 14% 1	650
June	1st to 10th	Night	9% 5% 25% 49% 12% 1	599
	11th to 20th	Night	9% 5% 30% 42% 14% 1	570
	21st to end	Night	11% 4 27% 42% 15%	570
July	1st to 10th	Night	10% 2 13% 42% 29% 5%	555
	11th to 20th	Night	8% 2 19% 41% 26% 3	552
	21st to end	Night	6% 1 17% 46% 29% 2	624
August	1st to 10th	Night	6% 2 15% 42% 31% 4	567
	11th to 20th	Night	8% 2 14% 41% 30% 5%	564
	21st to end	Night	9% 1 15% 42% 30% 2	627
September	1st to 10th	Night	12% 3 18% 38% 27% 4	570
	11th to 20th	Night	10% 4 21% 36% 25% 4	612
	21st to end	Night	11% 8% 27% 35% 18% 2	760
October	1st to 10th	Night	13% 7% 29% 33% 17% 2	760
	11th to 20th	Night	20% 11% 31% 26% 12%	760
	21st to end	Night	25% 11% 32% 25% 8%	836
November	1st to 10th	Night	17% 6% 41% 26% 9% 1	780
	11th to 20th	Night	20% 13% 38% 25% 5%	800
	21st to end	Night	22% 12% 34% 26% 6%	950
December	1st to 10th	Night	21% 12% 37% 24% 5%	1000
	11th to 20th	Night	23% 11% 34% 26% 6%	1000
	21st to end	Night	28% 13% 34% 23% 2	1100

Page generated at 2025-06-07 09:28:18. Version ac07

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