Rattle Snake Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rattle Snake Springs clear sky chart from 2005-11-06 to 2024-01-14.

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	4 3 1 3 3 2 3 4 5% 7% 63%	74884
	Night	5% 3 1 3 3 2 3 4 5% 7% 64%	74880
Transparency	Day	19% 5% 9% 17% 25% 24%	74623
	Night	19% 5% 8% 16% 25% 26%	74664
Seeing	Day	6% 8% 22% 31% 25% 8%	13670
	Night	6% 7% 26% 38% 22% 2	23902

By Month

Percentage Cloud Cover SW (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	4 4 2 4 3 2 3 3 3 6% 65%	1708
	11th to 20th	Day	4 3 2 2 2 2 3 3 4 6% 69%	1647
	21st to end	Day	5% 5% 2 3 3 2 2 3 4 5% 66%	1957
February	1st to 10th	Day	3 3 1 4 2 2 3 3 4 6% 70%	1800
	11th to 20th	Day	3 5% 2 4 3 2 3 4 5% 6% 62%	1749
	21st to end	Day	2 4 1 3 3 2 3 3 3 4 71%	1480
March	1st to 10th	Day	4 3 2 4 4 2 4 4 5% 7% 61%	1800
	11th to 20th	Day	6% 4 2 4 4 2 3 3 4 8% 60%	1959
	21st to end	Day	3 3 1 3 3 2 3 3 5% 6% 67%	2326
April	1st to 10th	Day	3 3 2 2 2 1 3 4 5% 6% 70%	2160
	11th to 20th	Day	4 3 1 3 2 2 3 2 3 4 73%	2131
	21st to end	Day	2 2 1 2 2 1 3 3 3 5% 76%	2160
May	1st to 10th	Day	4 2 1 2 3 1 3 3 4 6% 71%	2160
	11th to 20th	Day	6% 2 1 3 3 2 3 4 5% 7% 64%	2126
	21st to end	Day	4 2 1 1 3 2 3 4 5% 6% 68%	2531
June	1st to 10th	Day	2 2 1 2 2 2 3 4 7% 10% 66%	2358
	11th to 20th	Day	2 2 1 2 3 2 3 5% 5% 8% 68%	2520
	21st to end	Day	5% 2 1 3 3 3 5% 4 6% 9% 59%	2520
July	1st to 10th	Day	5% 2 2 4 4 3 5% 7% 9% 12% 47%	2416
	11th to 20th	Day	5% 2 1 3 4 3 5% 5% 7% 11% 55%	2340
	21st to end	Day	5% 3 2 3 3 3 5% 5% 7% 11% 54%	2349
August	1st to 10th	Day	4 1 1 2 4 3 4 6% 8% 11% 56%	2149
	11th to 20th	Day	4 3 2 4 5% 4 5% 7% 10% 12% 44%	2123
	21st to end	Day	6% 3 1 4 5% 3 5% 7% 8% 11% 47%	2376
September	1st to 10th	Day	8% 3 1 3 5% 3 5% 5% 6% 9% 52%	2160
	11th to 20th	Day	9% 5% 1 3 4 3 4 6% 6% 8% 49%	2089
	21st to end	Day	8% 2 1 2 3 2 3 4 5% 5% 66%	1980
October	1st to 10th	Day	6% 3 1 2 3 2 3 3 5% 7% 64%	1953
	11th to 20th	Day	5% 4 1 3 2 1 2 3 2 4 72%	1800
	21st to end	Day	4 3 1 2 3 1 2 2 2 4 76%	1980
November	1st to 10th	Day	6% 3 1 2 2 2 2 3 3 5% 72%	1788
	11th to 20th	Day	2 3 1 3 3 2 3 3 5% 5% 69%	1710
	21st to end	Day	5% 3 2 2 2 2 3 4 5% 5% 65%	1710
December	1st to 10th	Day	6% 5% 2 4 2 2 3 4 5% 6% 61%	1710
	11th to 20th	Day	2 3 1 3 3 2 4 5% 7% 8% 61%	2161
	21st to end	Day	3 3 1 3 2 1 2 3 4 6% 71%	2998
January	1st to 10th	Night	5% 4 2 3 4 2 3 4 3 6% 63%	2457
	11th to 20th	Night	5% 4 2 3 3 1 4 3 4 6% 65%	2391
	21st to end	Night	5% 3 2 2 2 2 3 3 5% 6% 68%	2394
February	1st to 10th	Night	3 4 1 3 2 2 3 3 5% 7% 69%	2160
	11th to 20th	Night	5% 3 2 4 2 2 3 4 5% 6% 64%	2098
	21st to end	Night	4 3 2 3 3 2 3 4 4 6% 67%	1776
March	1st to 10th	Night	5% 4 2 2 4 2 4 4 4 7% 62%	2160
	11th to 20th	Night	6% 3 1 3 4 3 4 4 5% 6% 62%	1995
	21st to end	Night	2 3 1 3 2 2 3 4 5% 6% 68%	2030
April	1st to 10th	Night	3 3 1 3 3 2 3 3 4 6% 69%	1800
	11th to 20th	Night	5% 2 1 3 2 1 3 4 4 5% 69%	1777
	21st to end	Night	2 1 1 3 2 2 2 3 3 6% 76%	1800
May	1st to 10th	Night	3 2 1 3 2 2 3 4 3 6% 71%	1800
	11th to 20th	Night	7% 2 1 2 3 2 3 4 5% 7% 65%	1766
	21st to end	Night	4 2 1 2 3 2 3 4 6% 7% 67%	1745
June	1st to 10th	Night	2 2 1 3 3 3 4 5% 8% 10% 59%	1595
	11th to 20th	Night	2 2 1 3 3 1 3 4 6% 7% 68%	1440
	21st to end	Night	4 2 1 3 3 2 4 4 7% 11% 59%	1440
July	1st to 10th	Night	5% 2 1 4 4 3 4 5% 9% 12% 52%	1537
	11th to 20th	Night	3 2 2 3 4 3 5% 5% 8% 12% 54%	1620
	21st to end	Night	4 2 2 4 5% 3 4 6% 7% 12% 50%	1964
August	1st to 10th	Night	3 2 1 4 4 4 4 5% 8% 13% 52%	1790
	11th to 20th	Night	4 3 1 3 5% 3 5% 6% 8% 13% 48%	1778
	21st to end	Night	5% 3 2 4 4 3 6% 6% 9% 12% 47%	1980
September	1st to 10th	Night	8% 4 2 3 4 3 4 4 6% 8% 55%	1800
	11th to 20th	Night	8% 4 1 4 4 3 3 4 6% 9% 53%	1868
	21st to end	Night	7% 3 2 3 3 2 3 4 5% 7% 61%	1980
October	1st to 10th	Night	7% 3 1 3 2 2 3 4 4 6% 65%	2003
	11th to 20th	Night	7% 3 1 2 2 1 2 2 3 5% 72%	2160
	21st to end	Night	5% 3 1 2 2 1 2 3 3 4 73%	2376
November	1st to 10th	Night	6% 2 1 2 1 2 3 4 5% 74%	2267
	11th to 20th	Night	2 3 1 2 3 2 3 4 5% 5% 71%	2470
	21st to end	Night	6% 4 1 2 3 2 3 3 4 4 68%	2470
December	1st to 10th	Night	7% 4 2 3 3 2 3 4 5% 8% 61%	2470
	11th to 20th	Night	3 3 1 3 4 2 3 4 4 7% 64%	3036
	21st to end	Night	2 3 1 2 3 2 3 3 3 5% 73%	4687

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	22% 3 6% 14% 32% 23%	1709
	11th to 20th	Day	17% 4 5% 15% 33% 26%	1647
	21st to end	Day	22% 3 6% 12% 30% 27%	1957
February	1st to 10th	Day	17% 3 6% 16% 25% 32%	1800
	11th to 20th	Day	23% 4 7% 14% 23% 28%	1759
	21st to end	Day	17% 3 3 11% 24% 41%	1480
March	1st to 10th	Day	22% 5% 7% 12% 28% 27%	1800
	11th to 20th	Day	23% 3 6% 13% 24% 31%	1959
	21st to end	Day	18% 2 6% 13% 26% 33%	2326
April	1st to 10th	Day	15% 3 6% 12% 29% 35%	2160
	11th to 20th	Day	16% 3 4 10% 25% 41%	2134
	21st to end	Day	12% 3 6% 12% 30% 38%	2160
May	1st to 10th	Day	15% 3 5% 10% 23% 44%	2160
	11th to 20th	Day	21% 5% 8% 14% 25% 28%	2129
	21st to end	Day	16% 5% 8% 18% 17% 37%	2531
June	1st to 10th	Day	13% 6% 10% 21% 24% 25%	2358
	11th to 20th	Day	14% 4 7% 15% 22% 38%	2520
	21st to end	Day	21% 6% 10% 18% 25% 21%	2520
July	1st to 10th	Day	25% 10% 16% 23% 20% 6%	2352
	11th to 20th	Day	19% 9% 14% 22% 24% 11%	2271
	21st to end	Day	21% 9% 18% 31% 19% 3	2219
August	1st to 10th	Day	19% 8% 16% 31% 22% 4	2136
	11th to 20th	Day	27% 9% 20% 24% 15% 4	2123
	21st to end	Day	26% 11% 17% 23% 17% 7%	2376
September	1st to 10th	Day	27% 8% 13% 18% 19% 15%	2160
	11th to 20th	Day	30% 7% 11% 17% 23% 11%	2089
	21st to end	Day	20% 5% 7% 17% 32% 19%	1980
October	1st to 10th	Day	20% 6% 11% 16% 24% 23%	1953
	11th to 20th	Day	19% 3 5% 13% 27% 33%	1800
	21st to end	Day	15% 3 4 17% 32% 30%	1980
November	1st to 10th	Day	16% 3 5% 18% 29% 29%	1788
	11th to 20th	Day	17% 5% 7% 17% 28% 26%	1710
	21st to end	Day	20% 4 7% 15% 28% 26%	1710
December	1st to 10th	Day	23% 5% 7% 20% 29% 16%	1710
	11th to 20th	Day	19% 6% 10% 18% 26% 20%	2159
	21st to end	Day	15% 4 6% 18% 32% 27%	2998
January	1st to 10th	Night	22% 4 6% 13% 30% 25%	2457
	11th to 20th	Night	22% 3 5% 12% 32% 26%	2391
	21st to end	Night	18% 4 6% 13% 32% 27%	2394
February	1st to 10th	Night	16% 3 8% 14% 24% 35%	2160
	11th to 20th	Night	21% 5% 7% 11% 25% 31%	2098
	21st to end	Night	18% 4 5% 10% 21% 43%	1776
March	1st to 10th	Night	21% 5% 6% 13% 23% 32%	2160
	11th to 20th	Night	24% 4 5% 13% 24% 30%	1995
	21st to end	Night	15% 4 7% 14% 24% 36%	2030
April	1st to 10th	Night	18% 3 5% 11% 24% 38%	1800
	11th to 20th	Night	16% 4 7% 12% 21% 39%	1777
	21st to end	Night	13% 3 4 14% 27% 39%	1800
May	1st to 10th	Night	16% 4 5% 10% 20% 45%	1800
	11th to 20th	Night	20% 5% 8% 14% 23% 30%	1767
	21st to end	Night	15% 7% 10% 15% 19% 34%	1746
June	1st to 10th	Night	17% 7% 12% 18% 22% 23%	1595
	11th to 20th	Night	15% 4 8% 14% 23% 37%	1440
	21st to end	Night	18% 6% 16% 19% 22% 19%	1440
July	1st to 10th	Night	21% 9% 17% 25% 22% 5%	1492
	11th to 20th	Night	19% 10% 15% 21% 24% 11%	1566
	21st to end	Night	22% 10% 17% 28% 21% 4	1855
August	1st to 10th	Night	21% 6% 13% 31% 23% 6%	1779
	11th to 20th	Night	24% 8% 19% 27% 17% 5%	1778
	21st to end	Night	26% 9% 14% 25% 19% 8%	1980
September	1st to 10th	Night	26% 8% 12% 18% 19% 18%	1800
	11th to 20th	Night	26% 7% 13% 21% 20% 13%	1868
	21st to end	Night	22% 6% 9% 17% 28% 19%	1980
October	1st to 10th	Night	21% 5% 9% 16% 24% 26%	2003
	11th to 20th	Night	18% 3 5% 14% 26% 34%	2160
	21st to end	Night	17% 2 5% 14% 29% 33%	2376
November	1st to 10th	Night	14% 3 5% 15% 30% 33%	2267
	11th to 20th	Night	15% 3 6% 17% 30% 30%	2470
	21st to end	Night	20% 4 6% 15% 28% 27%	2470
December	1st to 10th	Night	22% 4 6% 18% 25% 24%	2470
	11th to 20th	Night	20% 3 6% 19% 29% 23%	3037
	21st to end	Night	14% 4 6% 13% 36% 27%	4687

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	9% 14% 33% 34% 10%	270
	11th to 20th	Day	11% 14% 31% 33% 12% 1	249
	21st to end	Day	3 15% 36% 34% 11% 2	264
February	1st to 10th	Day	3 12% 35% 35% 14% 2	240
	11th to 20th	Day	11% 15% 36% 28% 9% 1	240
	21st to end	Day	8% 22% 33% 28% 8% 1	198
March	1st to 10th	Day	10% 12% 36% 32% 9% 1	240
	11th to 20th	Day	13% 16% 33% 27% 9% 2	399
	21st to end	Day	5% 25% 39% 24% 6% 1	462
April	1st to 10th	Day	7% 19% 37% 30% 6% 1	420
	11th to 20th	Day	5% 24% 37% 25% 7% 1	412
	21st to end	Day	5% 16% 40% 27% 11% 1	420
May	1st to 10th	Day	4 14% 39% 31% 11%	423
	11th to 20th	Day	6% 9% 30% 34% 17% 3	449
	21st to end	Day	6% 5% 30% 41% 18% 1	679
June	1st to 10th	Day	3 2 17% 44% 31% 3	630
	11th to 20th	Day	2 3 18% 40% 32% 6%	630
	21st to end	Day	5% 1 12% 34% 38% 9%	630
July	1st to 10th	Day	5% 6% 26% 45% 17%	522
	11th to 20th	Day	3 3 27% 42% 25%	444
	21st to end	Day	2 1 2 28% 44% 24%	487
August	1st to 10th	Day	3 4 21% 46% 26%	447
	11th to 20th	Day	4 2 7% 26% 42% 19%	437
	21st to end	Day	5% 1 6% 22% 40% 26%	495
September	1st to 10th	Day	8% 1 8% 30% 38% 16%	450
	11th to 20th	Day	5% 1 6% 30% 44% 15%	379
	21st to end	Day	8% 1 10% 27% 35% 18%	270
October	1st to 10th	Day	11% 3 16% 28% 34% 8%	270
	11th to 20th	Day	9% 4 17% 35% 27% 7%	270
	21st to end	Day	7% 8% 25% 27% 24% 9%	297
November	1st to 10th	Day	12% 8% 27% 29% 20% 4	270
	11th to 20th	Day	5% 11% 22% 34% 23% 5%	270
	21st to end	Day	10% 14% 33% 27% 13% 3	270
December	1st to 10th	Day	13% 13% 20% 37% 16% 2	270
	11th to 20th	Day	4 16% 26% 40% 13%	270
	21st to end	Day	7% 14% 35% 32% 10% 1	297
January	1st to 10th	Night	8% 9% 32% 37% 13% 1	760
	11th to 20th	Night	7% 9% 37% 34% 11% 2	736
	21st to end	Night	6% 10% 35% 37% 11% 1	792
February	1st to 10th	Night	5% 11% 36% 34% 13% 1	720
	11th to 20th	Night	8% 10% 37% 37% 7% 1	704
	21st to end	Night	6% 18% 43% 27% 6% 1	592
March	1st to 10th	Night	8% 11% 37% 36% 8% 1	720
	11th to 20th	Night	9% 14% 29% 34% 14%	720
	21st to end	Night	3 12% 43% 34% 7%	644
April	1st to 10th	Night	4 12% 43% 36% 5%	540
	11th to 20th	Night	5% 11% 42% 35% 6%	533
	21st to end	Night	2 11% 44% 34% 8%	540
May	1st to 10th	Night	4 5% 43% 41% 7%	540
	11th to 20th	Night	7% 5% 29% 44% 15%	531
	21st to end	Night	5% 4 28% 51% 12%	584
June	1st to 10th	Night	2 3 19% 54% 20% 1	540
	11th to 20th	Night	2 1 20% 56% 20%	540
	21st to end	Night	4 1 13% 52% 30% 1	540
July	1st to 10th	Night	5% 7% 42% 43% 3	525
	11th to 20th	Night	3 5% 40% 49% 3	522
	21st to end	Night	4 1 5% 32% 54% 5%	591
August	1st to 10th	Night	4 4 26% 62% 5%	537
	11th to 20th	Night	4 4 25% 58% 8%	534
	21st to end	Night	6% 1 4 29% 55% 6%	594
September	1st to 10th	Night	8% 1 5% 36% 45% 6%	540
	11th to 20th	Night	8% 1 4 40% 45% 3	540
	21st to end	Night	8% 1 9% 42% 36% 4	540
October	1st to 10th	Night	9% 2 17% 45% 25% 2	563
	11th to 20th	Night	8% 5% 18% 44% 22% 3	720
	21st to end	Night	6% 7% 21% 35% 25% 6%	792
November	1st to 10th	Night	6% 4 23% 39% 25% 3	787
	11th to 20th	Night	4 6% 25% 43% 20% 2	950
	21st to end	Night	8% 10% 28% 35% 16% 2	950
December	1st to 10th	Night	9% 8% 30% 36% 15% 1	950
	11th to 20th	Night	6% 10% 35% 36% 11% 1	950
	21st to end	Night	5% 13% 36% 36% 9% 1	1041

Page generated at 2024-01-11 11:31:57. Version ac07

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