Government Canyon State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Government Canyon State Natural Area clear sky chart from 2005-11-06 to 2024-01-22.

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% 5% 2 5% 5% 3 4 4 5% 7% 46%	74943
	Night	15% 5% 2 4 4 2 3 4 4 7% 51%	75021
Transparency	Day	38% 5% 9% 20% 18% 9%	74668
	Night	34% 5% 11% 20% 18% 12%	74816
Seeing	Day	16% 7% 24% 31% 18% 3	13660
	Night	18% 7% 25% 35% 14% 1	23751

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	16% 6% 2 4 4 2 4 3 3 5% 51%	1707
	11th to 20th	Day	19% 6% 3 5% 3 2 3 2 3 4 48%	1710
	21st to end	Day	16% 5% 2 3 3 2 4 4 4 6% 50%	1990
February	1st to 10th	Day	20% 7% 2 4 4 3 4 4 3 4 46%	1800
	11th to 20th	Day	20% 7% 2 5% 4 2 4 4 5% 6% 42%	1749
	21st to end	Day	19% 6% 2 4 3 1 3 3 4 5% 50%	1480
March	1st to 10th	Day	21% 8% 3 4 4 2 3 3 4 5% 42%	1918
	11th to 20th	Day	17% 6% 2 6% 4 3 3 4 4 6% 45%	1980
	21st to end	Day	19% 6% 2 5% 4 2 3 4 5% 6% 46%	2178
April	1st to 10th	Day	16% 7% 2 6% 5% 3 4 3 4 6% 45%	1980
	11th to 20th	Day	21% 6% 3 4 4 2 4 4 4 5% 43%	2006
	21st to end	Day	18% 6% 2 5% 5% 3 4 4 4 5% 44%	2240
May	1st to 10th	Day	18% 5% 3 5% 5% 3 4 4 5% 7% 40%	2340
	11th to 20th	Day	15% 7% 2 6% 6% 4 5% 4 5% 8% 38%	2302
	21st to end	Day	18% 5% 3 5% 5% 3 6% 5% 6% 8% 35%	2531
June	1st to 10th	Day	8% 4 2 4 5% 4 6% 6% 7% 10% 46%	2340
	11th to 20th	Day	8% 4 2 6% 6% 3 6% 6% 7% 9% 43%	2340
	21st to end	Day	10% 6% 4 6% 6% 4 6% 6% 6% 8% 38%	2340
July	1st to 10th	Day	12% 7% 3 7% 7% 3 5% 6% 7% 7% 37%	2340
	11th to 20th	Day	6% 3 2 3 5% 4 6% 5% 7% 11% 48%	2340
	21st to end	Day	6% 3 2 3 5% 3 5% 5% 7% 11% 48%	2546
August	1st to 10th	Day	2 2 1 3 4 2 4 4 6% 10% 60%	2227
	11th to 20th	Day	7% 3 2 4 5% 4 5% 6% 7% 11% 48%	2123
	21st to end	Day	7% 4 2 6% 6% 4 5% 7% 7% 10% 42%	2312
September	1st to 10th	Day	12% 6% 2 7% 6% 4 5% 4 7% 7% 39%	1980
	11th to 20th	Day	11% 6% 3 6% 6% 4 5% 6% 7% 7% 39%	1980
	21st to end	Day	9% 4 2 5% 6% 4 4 5% 6% 8% 47%	1980
October	1st to 10th	Day	8% 4 2 4 5% 3 5% 5% 4 8% 53%	1980
	11th to 20th	Day	16% 5% 2 4 4 3 4 4 4 5% 50%	1908
	21st to end	Day	13% 4 2 4 3 2 4 4 4 6% 57%	1980
November	1st to 10th	Day	16% 8% 3 5% 5% 2 4 3 4 6% 44%	1858
	11th to 20th	Day	16% 5% 2 4 4 3 3 5% 4 5% 48%	1742
	21st to end	Day	20% 7% 2 4 4 3 4 3 4 5% 45%	1710
December	1st to 10th	Day	19% 6% 2 4 4 3 3 3 5% 7% 46%	1710
	11th to 20th	Day	18% 7% 2 5% 4 2 4 4 3 5% 45%	2161
	21st to end	Day	17% 6% 2 4 2 2 2 3 3 4 55%	3135
January	1st to 10th	Night	17% 4 2 3 3 2 3 3 4 5% 54%	2458
	11th to 20th	Night	17% 6% 3 4 3 2 4 3 3 5% 51%	2470
	21st to end	Night	19% 6% 2 4 3 2 3 3 4 5% 49%	2415
February	1st to 10th	Night	19% 6% 1 3 3 2 3 3 4 6% 50%	2160
	11th to 20th	Night	20% 6% 2 4 3 2 3 2 3 5% 49%	2098
	21st to end	Night	20% 6% 2 4 3 2 3 4 3 6% 47%	1776
March	1st to 10th	Night	20% 6% 2 4 4 2 3 4 4 6% 44%	2040
	11th to 20th	Night	19% 6% 2 5% 4 2 3 3 4 5% 46%	1980
	21st to end	Night	19% 5% 2 4 3 2 3 3 4 7% 49%	2178
April	1st to 10th	Night	15% 5% 2 5% 4 2 4 5% 4 7% 48%	1980
	11th to 20th	Night	20% 6% 3 4 3 2 3 4 3 5% 46%	1898
	21st to end	Night	21% 5% 3 5% 4 2 3 4 3 5% 47%	1719
May	1st to 10th	Night	16% 5% 2 5% 4 3 4 4 5% 7% 45%	1620
	11th to 20th	Night	15% 6% 2 3 5% 3 4 4 5% 9% 45%	1593
	21st to end	Night	16% 6% 2 5% 4 2 3 4 6% 10% 42%	1745
June	1st to 10th	Night	7% 3 1 3 4 1 3 4 6% 8% 59%	1620
	11th to 20th	Night	7% 4 2 3 4 2 3 4 5% 9% 58%	1620
	21st to end	Night	9% 3 2 4 4 3 4 5% 7% 10% 47%	1620
July	1st to 10th	Night	9% 5% 3 4 5% 3 4 6% 5% 11% 44%	1620
	11th to 20th	Night	4 2 1 3 3 3 5% 4 5% 8% 61%	1620
	21st to end	Night	6% 2 1 3 2 2 4 4 7% 11% 57%	1772
August	1st to 10th	Night	2 2 1 2 3 2 3 4 5% 9% 68%	1707
	11th to 20th	Night	6% 3 2 4 4 3 4 6% 6% 11% 53%	1778
	21st to end	Night	7% 4 2 5% 5% 3 5% 5% 6% 11% 48%	2042
September	1st to 10th	Night	9% 6% 2 5% 5% 3 4 5% 6% 8% 47%	1980
	11th to 20th	Night	11% 6% 2 5% 6% 3 5% 4 5% 8% 44%	1980
	21st to end	Night	8% 5% 2 5% 5% 3 4 5% 6% 8% 50%	1980
October	1st to 10th	Night	8% 4 2 3 3 2 4 4 5% 7% 58%	1980
	11th to 20th	Night	14% 5% 2 3 3 2 3 4 4 6% 53%	2033
	21st to end	Night	16% 4 1 3 2 1 2 2 3 4 61%	2376
November	1st to 10th	Night	15% 6% 2 5% 3 1 2 3 3 5% 53%	2220
	11th to 20th	Night	13% 5% 2 4 3 2 4 4 4 6% 54%	2435
	21st to end	Night	20% 4 2 4 4 3 3 4 4 6% 46%	2470
December	1st to 10th	Night	17% 5% 1 4 3 2 3 3 4 6% 51%	2470
	11th to 20th	Night	19% 7% 3 5% 4 2 3 3 3 5% 47%	3036
	21st to end	Night	20% 6% 1 3 2 2 2 3 3 6% 52%	4532

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	36% 3 3 19% 21% 18%	1708
	11th to 20th	Day	42% 2 5% 14% 20% 17%	1710
	21st to end	Day	36% 3 6% 14% 24% 16%	1990
February	1st to 10th	Day	43% 3 5% 12% 21% 16%	1800
	11th to 20th	Day	43% 3 5% 17% 18% 13%	1759
	21st to end	Day	39% 3 7% 17% 19% 16%	1480
March	1st to 10th	Day	46% 3 8% 14% 18% 12%	1918
	11th to 20th	Day	41% 4 7% 16% 16% 17%	1980
	21st to end	Day	40% 4 8% 17% 18% 13%	2178
April	1st to 10th	Day	43% 3 8% 18% 17% 11%	1980
	11th to 20th	Day	44% 4 5% 17% 17% 13%	2006
	21st to end	Day	43% 4 6% 19% 17% 11%	2240
May	1st to 10th	Day	45% 5% 8% 17% 18% 7%	2340
	11th to 20th	Day	44% 6% 9% 19% 18% 4	2306
	21st to end	Day	47% 6% 10% 22% 15% 1	2531
June	1st to 10th	Day	32% 6% 13% 27% 19% 3	2340
	11th to 20th	Day	35% 6% 12% 26% 17% 4	2340
	21st to end	Day	43% 7% 10% 24% 13% 3	2340
July	1st to 10th	Day	43% 7% 15% 24% 10% 2	2276
	11th to 20th	Day	28% 6% 18% 27% 19% 2	2271
	21st to end	Day	25% 7% 20% 34% 12% 1	2405
August	1st to 10th	Day	20% 5% 16% 40% 19% 1	2213
	11th to 20th	Day	28% 7% 18% 30% 12% 3	2123
	21st to end	Day	35% 7% 17% 25% 13% 3	2312
September	1st to 10th	Day	42% 6% 10% 19% 16% 7%	1980
	11th to 20th	Day	40% 8% 11% 20% 17% 5%	1980
	21st to end	Day	34% 5% 10% 22% 18% 10%	1980
October	1st to 10th	Day	30% 6% 10% 20% 26% 8%	1980
	11th to 20th	Day	37% 4 8% 17% 19% 16%	1908
	21st to end	Day	30% 4 4 16% 25% 21%	1980
November	1st to 10th	Day	42% 3 7% 21% 16% 11%	1858
	11th to 20th	Day	38% 4 7% 15% 21% 15%	1742
	21st to end	Day	43% 4 5% 15% 19% 13%	1710
December	1st to 10th	Day	40% 3 8% 20% 20% 10%	1710
	11th to 20th	Day	43% 4 6% 10% 21% 16%	2159
	21st to end	Day	35% 2 5% 16% 27% 15%	3135
January	1st to 10th	Night	34% 3 6% 16% 22% 20%	2458
	11th to 20th	Night	38% 3 5% 17% 21% 17%	2470
	21st to end	Night	39% 3 4 14% 20% 19%	2415
February	1st to 10th	Night	37% 4 6% 13% 21% 19%	2160
	11th to 20th	Night	40% 2 5% 17% 18% 17%	2098
	21st to end	Night	40% 4 6% 16% 18% 17%	1776
March	1st to 10th	Night	42% 4 8% 16% 18% 11%	2040
	11th to 20th	Night	42% 4 7% 14% 16% 18%	1980
	21st to end	Night	38% 3 10% 17% 18% 15%	2178
April	1st to 10th	Night	37% 4 10% 19% 16% 14%	1980
	11th to 20th	Night	41% 4 7% 14% 17% 16%	1898
	21st to end	Night	41% 4 8% 19% 16% 12%	1719
May	1st to 10th	Night	38% 5% 11% 20% 16% 10%	1620
	11th to 20th	Night	38% 6% 11% 24% 17% 5%	1594
	21st to end	Night	38% 6% 15% 26% 13% 1	1746
June	1st to 10th	Night	23% 6% 17% 31% 20% 3	1620
	11th to 20th	Night	25% 5% 15% 30% 20% 5%	1620
	21st to end	Night	31% 6% 18% 28% 14% 3	1620
July	1st to 10th	Night	33% 7% 20% 29% 9% 2	1575
	11th to 20th	Night	20% 8% 21% 31% 19% 2	1566
	21st to end	Night	19% 8% 27% 34% 11% 1	1673
August	1st to 10th	Night	14% 7% 22% 40% 16% 1	1697
	11th to 20th	Night	25% 8% 23% 30% 12% 2	1778
	21st to end	Night	29% 9% 23% 25% 11% 3	2042
September	1st to 10th	Night	35% 7% 15% 21% 16% 6%	1980
	11th to 20th	Night	38% 8% 15% 21% 14% 4	1980
	21st to end	Night	31% 6% 13% 22% 18% 10%	1980
October	1st to 10th	Night	26% 5% 10% 27% 20% 11%	1980
	11th to 20th	Night	32% 5% 9% 18% 19% 17%	2033
	21st to end	Night	30% 2 5% 15% 25% 22%	2376
November	1st to 10th	Night	35% 3 7% 19% 21% 14%	2220
	11th to 20th	Night	33% 4 9% 19% 20% 16%	2435
	21st to end	Night	40% 3 7% 16% 19% 14%	2470
December	1st to 10th	Night	36% 3 8% 19% 21% 13%	2470
	11th to 20th	Night	42% 3 4 14% 17% 20%	3037
	21st to end	Night	36% 3 5% 13% 29% 15%	4532

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	27% 13% 34% 20% 5%	270
	11th to 20th	Day	28% 15% 31% 20% 6% 1	270
	21st to end	Day	22% 17% 36% 18% 7%	267
February	1st to 10th	Day	32% 15% 30% 18% 5%	240
	11th to 20th	Day	33% 17% 34% 13% 4 1	240
	21st to end	Day	31% 21% 35% 11% 2	198
March	1st to 10th	Day	29% 16% 42% 12% 1	240
	11th to 20th	Day	22% 18% 45% 13% 3	240
	21st to end	Day	23% 19% 41% 16% 2	264
April	1st to 10th	Day	25% 14% 41% 17% 2	240
	11th to 20th	Day	24% 16% 37% 20% 2	284
	21st to end	Day	22% 13% 42% 20% 3	500
May	1st to 10th	Day	20% 11% 40% 25% 5%	603
	11th to 20th	Day	20% 8% 33% 31% 7% 1	625
	21st to end	Day	19% 5% 32% 31% 12% 1	679
June	1st to 10th	Day	9% 2 21% 44% 22% 2	630
	11th to 20th	Day	9% 3 22% 47% 17% 2	630
	21st to end	Day	11% 4 17% 35% 27% 5%	630
July	1st to 10th	Day	13% 2 12% 37% 30% 6%	621
	11th to 20th	Day	6% 1 7% 40% 41% 5%	618
	21st to end	Day	4 1 7% 41% 40% 7%	684
August	1st to 10th	Day	3 1 7% 42% 39% 8%	525
	11th to 20th	Day	7% 2 7% 43% 33% 8%	437
	21st to end	Day	5% 2 5% 38% 41% 10%	431
September	1st to 10th	Day	11% 1 7% 29% 42% 9%	270
	11th to 20th	Day	7% 2 6% 37% 41% 6%	270
	21st to end	Day	11% 2 11% 35% 33% 8%	270
October	1st to 10th	Day	9% 1 20% 40% 26% 5%	270
	11th to 20th	Day	13% 5% 24% 41% 14% 2	270
	21st to end	Day	24% 11% 27% 25% 11% 2	297
November	1st to 10th	Day	20% 8% 31% 29% 10% 2	270
	11th to 20th	Day	26% 7% 33% 25% 8% 2	270
	21st to end	Day	30% 16% 33% 14% 7% 1	270
December	1st to 10th	Day	21% 11% 31% 27% 8% 1	270
	11th to 20th	Day	29% 11% 33% 21% 5%	270
	21st to end	Day	24% 10% 38% 22% 4 2	297
January	1st to 10th	Night	21% 10% 25% 33% 10% 1	950
	11th to 20th	Night	23% 11% 29% 29% 8%	950
	21st to end	Night	25% 11% 25% 32% 6%	815
February	1st to 10th	Night	26% 13% 27% 27% 7%	720
	11th to 20th	Night	27% 13% 31% 23% 5%	704
	21st to end	Night	28% 12% 36% 22% 2	592
March	1st to 10th	Night	26% 11% 35% 25% 4	600
	11th to 20th	Night	22% 12% 33% 30% 3	540
	21st to end	Night	21% 12% 38% 25% 3	594
April	1st to 10th	Night	17% 13% 43% 24% 4	540
	11th to 20th	Night	24% 12% 39% 23% 2	533
	21st to end	Night	24% 9% 40% 21% 6% 1	540
May	1st to 10th	Night	17% 9% 43% 28% 3	540
	11th to 20th	Night	18% 6% 37% 31% 8% 1	531
	21st to end	Night	16% 7% 36% 32% 9%	584
June	1st to 10th	Night	8% 1 28% 44% 18% 1	540
	11th to 20th	Night	7% 2 38% 41% 10% 1	540
	21st to end	Night	9% 3 24% 41% 21% 2	540
July	1st to 10th	Night	11% 2 15% 45% 24% 3	525
	11th to 20th	Night	4 1 12% 55% 26% 2	522
	21st to end	Night	7% 1 11% 53% 25% 3	591
August	1st to 10th	Night	2 1 12% 53% 30% 2	537
	11th to 20th	Night	7% 1 11% 50% 27% 4	534
	21st to end	Night	7% 1 6% 46% 35% 4	594
September	1st to 10th	Night	10% 2 7% 45% 31% 4	540
	11th to 20th	Night	13% 2 9% 41% 31% 3	540
	21st to end	Night	10% 1 12% 42% 30% 5%	540
October	1st to 10th	Night	8% 1 15% 48% 24% 3	540
	11th to 20th	Night	16% 4 22% 39% 18% 2	593
	21st to end	Night	19% 6% 24% 30% 18% 3	792
November	1st to 10th	Night	16% 6% 19% 37% 19% 2	740
	11th to 20th	Night	16% 8% 22% 38% 14% 2	915
	21st to end	Night	24% 9% 24% 30% 12% 1	950
December	1st to 10th	Night	22% 7% 25% 33% 12% 1	950
	11th to 20th	Night	29% 7% 24% 31% 9%	950
	21st to end	Night	22% 10% 25% 34% 8%	1045

Page generated at 2024-01-19 08:28:31. Version ac07

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