Rocky Mountain Star Stare
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rocky Mountain Star Stare clear sky chart from 2005-11-06 to 2024-07-03.

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	2 5% 2 5% 4 4 4 4 6% 8% 56%	89636
	Night	2 5% 2 5% 3 3 3 3 5% 7% 62%	89735
Transparency	Day	22% 8% 11% 23% 24% 11%	89349
	Night	20% 7% 11% 25% 26% 10%	89544
Seeing	Day	12% 17% 31% 25% 12% 3	14953
	Night	7% 14% 34% 30% 13% 2	25025

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	1 4 2 5% 3 2 3 2 4 8% 64%	2538
	11th to 20th	Day	3 2 4 3 3 3 3 5% 7% 68%	2773
	21st to end	Day	1 10% 4 6% 3 2 3 3 5% 6% 59%	3146
February	1st to 10th	Day	5% 3 6% 3 2 3 2 5% 8% 63%	1732
	11th to 20th	Day	1 3 2 4 3 2 3 3 6% 7% 66%	1849
	21st to end	Day	1 5% 2 6% 3 4 3 4 6% 8% 59%	1570
March	1st to 10th	Day	1 5% 3 4 3 3 4 4 5% 7% 63%	3130
	11th to 20th	Day	2 14% 4 6% 4 4 3 3 4 7% 47%	3485
	21st to end	Day	1 6% 2 5% 4 3 4 4 7% 8% 57%	4039
April	1st to 10th	Day	2 6% 2 5% 3 3 4 4 7% 8% 58%	2280
	11th to 20th	Day	3 6% 2 6% 4 4 5% 3 5% 9% 54%	2251
	21st to end	Day	3 8% 3 5% 4 4 5% 5% 7% 8% 48%	2280
May	1st to 10th	Day	4 9% 2 5% 3 3 4 3 7% 7% 51%	3881
	11th to 20th	Day	5% 6% 2 6% 5% 4 5% 5% 7% 9% 47%	4250
	21st to end	Day	3 3 1 3 3 3 4 4 7% 8% 62%	4825
June	1st to 10th	Day	3 3 1 4 5% 5% 5% 5% 7% 11% 51%	2660
	11th to 20th	Day	2 3 1 2 3 4 5% 4 6% 9% 61%	2660
	21st to end	Day	2 3 2 5% 5% 5% 6% 6% 9% 9% 49%	2660
July	1st to 10th	Day	5% 4 2 5% 4 5% 6% 6% 9% 9% 45%	2549
	11th to 20th	Day	3 4 2 5% 5% 5% 7% 6% 10% 10% 44%	2520
	21st to end	Day	4 5% 2 6% 6% 6% 8% 6% 10% 12% 34%	2587
August	1st to 10th	Day	5% 4 2 6% 6% 6% 7% 6% 9% 10% 40%	2280
	11th to 20th	Day	5% 5% 2 4 4 6% 5% 5% 8% 10% 47%	2123
	21st to end	Day	4 4 2 5% 4 4 6% 5% 7% 10% 47%	2376
September	1st to 10th	Day	4 5% 1 5% 4 4 5% 5% 7% 8% 52%	2160
	11th to 20th	Day	4 3 2 4 3 3 4 3 5% 7% 63%	2142
	21st to end	Day	3 3 2 3 3 3 3 3 5% 6% 66%	1980
October	1st to 10th	Day	5% 5% 2 3 4 4 4 4 5% 7% 58%	1820
	11th to 20th	Day	1 3 1 3 2 2 2 2 4 6% 74%	1800
	21st to end	Day	3 4 1 4 3 3 2 2 4 6% 68%	1967
November	1st to 10th	Day	1 2 1 2 2 3 2 3 5% 8% 70%	1673
	11th to 20th	Day	3 2 4 3 2 3 2 4 8% 69%	1710
	21st to end	Day	1 4 2 5% 2 2 3 3 6% 6% 65%	1700
December	1st to 10th	Day	1 3 2 4 3 3 3 2 4 7% 68%	1520
	11th to 20th	Day	1 4 2 4 2 3 3 3 6% 9% 64%	1926
	21st to end	Day	4 2 7% 4 3 3 3 4 7% 62%	2794
January	1st to 10th	Night	3 3 8% 4 3 3 3 5% 8% 61%	4417
	11th to 20th	Night	2 1 5% 3 3 3 2 4 7% 69%	4224
	21st to end	Night	1 4 3 6% 3 3 3 3 5% 8% 61%	4521
February	1st to 10th	Night	1 4 2 7% 3 3 3 2 5% 6% 65%	2447
	11th to 20th	Night	1 5% 2 7% 4 2 2 3 5% 6% 65%	2218
	21st to end	Night	4 3 5% 4 2 3 2 4 7% 66%	1884
March	1st to 10th	Night	1 7% 2 3 2 2 3 2 4 6% 67%	3734
	11th to 20th	Night	2 11% 3 6% 3 3 3 3 5% 6% 56%	3490
	21st to end	Night	1 6% 2 5% 2 3 3 3 5% 7% 64%	3605
April	1st to 10th	Night	1 4 2 4 3 2 2 2 5% 7% 67%	1900
	11th to 20th	Night	3 7% 2 5% 3 3 3 3 5% 8% 59%	1877
	21st to end	Night	3 8% 2 5% 2 3 4 3 5% 8% 58%	1900
May	1st to 10th	Night	5% 7% 2 4 2 3 4 3 4 5% 61%	3088
	11th to 20th	Night	9% 8% 2 4 4 3 3 4 5% 7% 54%	2651
	21st to end	Night	4 4 1 3 3 3 3 2 5% 7% 65%	2762
June	1st to 10th	Night	3 4 2 3 3 3 4 5% 6% 9% 58%	1520
	11th to 20th	Night	2 2 1 3 3 3 3 4 6% 9% 65%	1520
	21st to end	Night	3 3 1 4 4 4 5% 5% 8% 10% 53%	1520
July	1st to 10th	Night	6% 4 2 5% 5% 6% 5% 6% 8% 8% 45%	1456
	11th to 20th	Night	4 4 2 4 4 5% 4 5% 8% 10% 51%	1440
	21st to end	Night	5% 5% 2 5% 5% 6% 8% 7% 9% 12% 37%	1727
August	1st to 10th	Night	4 4 2 5% 4 6% 6% 6% 8% 10% 47%	1655
	11th to 20th	Night	5% 4 1 5% 4 5% 6% 5% 8% 11% 46%	1778
	21st to end	Night	4 4 2 5% 4 4 5% 6% 8% 11% 48%	1980
September	1st to 10th	Night	5% 4 2 3 3 3 5% 5% 6% 9% 54%	1800
	11th to 20th	Night	5% 4 1 3 2 2 3 4 5% 7% 63%	1818
	21st to end	Night	4 4 1 3 2 3 4 3 5% 5% 65%	1980
October	1st to 10th	Night	4 5% 2 4 2 3 3 3 4 6% 66%	2136
	11th to 20th	Night	1 2 1 3 1 2 2 3 4 6% 76%	2160
	21st to end	Night	3 5% 2 4 2 2 3 2 4 6% 67%	2376
November	1st to 10th	Night	1 3 1 2 2 2 2 3 4 7% 73%	2399
	11th to 20th	Night	1 3 1 3 3 2 2 2 4 6% 74%	2470
	21st to end	Night	1 5% 1 4 2 2 2 3 5% 7% 67%	2478
December	1st to 10th	Night	1 3 1 4 3 3 3 3 5% 8% 67%	2660
	11th to 20th	Night	1 5% 2 4 3 2 2 2 6% 9% 63%	3271
	21st to end	Night	1 4 2 5% 3 3 3 4 5% 7% 62%	4873

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	17% 6% 14% 30% 27% 6%	2539
	11th to 20th	Day	15% 6% 11% 32% 29% 6%	2773
	21st to end	Day	24% 7% 9% 29% 25% 6%	3146
February	1st to 10th	Day	21% 4 12% 30% 23% 10%	1732
	11th to 20th	Day	17% 6% 10% 27% 31% 9%	1859
	21st to end	Day	20% 6% 10% 20% 28% 16%	1570
March	1st to 10th	Day	17% 6% 9% 19% 37% 12%	3130
	11th to 20th	Day	32% 9% 10% 26% 20% 4	3485
	21st to end	Day	21% 6% 10% 32% 27% 4	4039
April	1st to 10th	Day	21% 7% 11% 23% 23% 14%	2280
	11th to 20th	Day	25% 7% 9% 24% 22% 12%	2254
	21st to end	Day	29% 8% 12% 20% 24% 7%	2280
May	1st to 10th	Day	26% 8% 10% 18% 22% 15%	3881
	11th to 20th	Day	27% 11% 13% 21% 18% 10%	4254
	21st to end	Day	15% 8% 10% 19% 25% 22%	4825
June	1st to 10th	Day	23% 9% 14% 21% 21% 12%	2660
	11th to 20th	Day	18% 8% 11% 16% 24% 23%	2660
	21st to end	Day	25% 8% 14% 21% 21% 12%	2660
July	1st to 10th	Day	30% 12% 13% 17% 17% 12%	2480
	11th to 20th	Day	25% 14% 15% 27% 14% 6%	2445
	21st to end	Day	33% 16% 23% 18% 8% 1	2443
August	1st to 10th	Day	31% 15% 19% 15% 13% 8%	2265
	11th to 20th	Day	29% 11% 14% 20% 19% 8%	2123
	21st to end	Day	26% 11% 15% 21% 23% 5%	2376
September	1st to 10th	Day	25% 9% 12% 23% 21% 11%	2160
	11th to 20th	Day	19% 7% 10% 20% 27% 17%	2142
	21st to end	Day	19% 6% 7% 21% 36% 11%	1980
October	1st to 10th	Day	22% 9% 11% 19% 27% 12%	1820
	11th to 20th	Day	13% 5% 6% 18% 40% 18%	1800
	21st to end	Day	19% 5% 7% 26% 31% 12%	1967
November	1st to 10th	Day	12% 4 9% 24% 35% 16%	1673
	11th to 20th	Day	15% 4 8% 32% 32% 10%	1710
	21st to end	Day	19% 5% 7% 20% 31% 17%	1700
December	1st to 10th	Day	17% 5% 12% 31% 25% 9%	1520
	11th to 20th	Day	16% 5% 15% 24% 32% 9%	1924
	21st to end	Day	19% 7% 10% 26% 24% 14%	2794
January	1st to 10th	Night	21% 6% 10% 27% 30% 6%	4417
	11th to 20th	Night	14% 5% 11% 34% 31% 6%	4224
	21st to end	Night	20% 9% 11% 32% 24% 5%	4521
February	1st to 10th	Night	22% 3 11% 30% 24% 10%	2447
	11th to 20th	Night	21% 5% 10% 28% 27% 8%	2218
	21st to end	Night	19% 3 8% 23% 34% 13%	1884
March	1st to 10th	Night	18% 4 8% 17% 42% 11%	3734
	11th to 20th	Night	28% 7% 11% 27% 24% 4	3490
	21st to end	Night	19% 6% 10% 36% 25% 3	3605
April	1st to 10th	Night	17% 4 11% 28% 27% 11%	1900
	11th to 20th	Night	23% 5% 11% 25% 26% 9%	1877
	21st to end	Night	25% 6% 15% 25% 22% 6%	1900
May	1st to 10th	Night	23% 6% 8% 23% 25% 15%	3088
	11th to 20th	Night	27% 8% 12% 30% 16% 8%	2652
	21st to end	Night	16% 7% 12% 20% 30% 16%	2762
June	1st to 10th	Night	21% 10% 14% 23% 18% 15%	1520
	11th to 20th	Night	15% 7% 11% 19% 26% 22%	1520
	21st to end	Night	24% 9% 14% 20% 20% 13%	1520
July	1st to 10th	Night	31% 12% 13% 17% 14% 12%	1416
	11th to 20th	Night	24% 10% 18% 28% 14% 7%	1392
	21st to end	Night	32% 18% 23% 19% 7% 1	1631
August	1st to 10th	Night	28% 15% 21% 16% 13% 7%	1646
	11th to 20th	Night	28% 10% 18% 23% 15% 6%	1778
	21st to end	Night	25% 12% 15% 24% 19% 6%	1980
September	1st to 10th	Night	24% 8% 15% 24% 21% 8%	1800
	11th to 20th	Night	18% 7% 11% 21% 25% 18%	1818
	21st to end	Night	20% 6% 10% 21% 34% 10%	1980
October	1st to 10th	Night	20% 6% 12% 21% 27% 13%	2136
	11th to 20th	Night	12% 3 9% 18% 39% 19%	2160
	21st to end	Night	21% 4 7% 25% 30% 13%	2376
November	1st to 10th	Night	12% 4 9% 26% 32% 17%	2399
	11th to 20th	Night	13% 3 7% 33% 32% 12%	2470
	21st to end	Night	17% 4 9% 22% 35% 13%	2478
December	1st to 10th	Night	16% 6% 12% 32% 24% 9%	2660
	11th to 20th	Night	16% 7% 11% 24% 33% 8%	3272
	21st to end	Night	19% 7% 14% 22% 26% 12%	4873

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	20% 21% 29% 20% 7% 3	270
	11th to 20th	Day	17% 24% 40% 15% 3 1	270
	21st to end	Day	7% 24% 39% 19% 9% 1	297
February	1st to 10th	Day	19% 30% 35% 13% 2 2	270
	11th to 20th	Day	21% 27% 37% 11% 3 1	270
	21st to end	Day	27% 25% 35% 12% 1	225
March	1st to 10th	Day	22% 25% 27% 20% 6%	270
	11th to 20th	Day	20% 21% 38% 17% 4 1	455
	21st to end	Day	25% 31% 30% 10% 3	506
April	1st to 10th	Day	20% 28% 35% 12% 4 1	460
	11th to 20th	Day	23% 27% 36% 11% 3 1	452
	21st to end	Day	18% 29% 33% 15% 4 1	460
May	1st to 10th	Day	15% 25% 37% 17% 5% 1	505
	11th to 20th	Day	13% 14% 33% 28% 10% 2	675
	21st to end	Day	11% 16% 30% 28% 13% 2	734
June	1st to 10th	Day	7% 12% 27% 32% 18% 4	680
	11th to 20th	Day	9% 12% 32% 29% 14% 4	680
	21st to end	Day	5% 12% 32% 29% 18% 4	680
July	1st to 10th	Day	6% 4 24% 38% 20% 7%	632
	11th to 20th	Day	4 4 17% 37% 28% 9%	618
	21st to end	Day	5% 3 14% 36% 30% 11%	529
August	1st to 10th	Day	6% 6% 23% 36% 21% 9%	447
	11th to 20th	Day	6% 5% 27% 33% 23% 5%	437
	21st to end	Day	7% 6% 24% 38% 20% 5%	495
September	1st to 10th	Day	6% 10% 27% 33% 18% 6%	450
	11th to 20th	Day	5% 12% 37% 28% 14% 3	432
	21st to end	Day	9% 9% 29% 30% 18% 7%	270
October	1st to 10th	Day	12% 15% 25% 27% 14% 6%	270
	11th to 20th	Day	11% 22% 34% 19% 9% 4	270
	21st to end	Day	12% 20% 39% 19% 10% 1	297
November	1st to 10th	Day	14% 21% 35% 22% 7% 1	270
	11th to 20th	Day	14% 19% 35% 20% 11% 1	270
	21st to end	Day	10% 20% 35% 28% 6% 1	270
December	1st to 10th	Day	14% 27% 32% 19% 8% 1	270
	11th to 20th	Day	14% 32% 33% 14% 5% 2	270
	21st to end	Day	19% 26% 36% 15% 3 1	297
January	1st to 10th	Night	7% 23% 35% 25% 8% 1	950
	11th to 20th	Night	8% 23% 40% 22% 6% 2	822
	21st to end	Night	5% 18% 41% 28% 7% 1	836
February	1st to 10th	Night	4 22% 48% 21% 4 1	760
	11th to 20th	Night	6% 24% 45% 17% 7%	744
	21st to end	Night	6% 19% 53% 19% 3	628
March	1st to 10th	Night	8% 24% 43% 20% 5% 1	760
	11th to 20th	Night	9% 13% 39% 29% 9% 1	760
	21st to end	Night	9% 18% 44% 25% 4	703
April	1st to 10th	Night	12% 16% 45% 24% 3	570
	11th to 20th	Night	14% 11% 42% 26% 7%	563
	21st to end	Night	11% 16% 34% 30% 8% 1	570
May	1st to 10th	Night	10% 11% 39% 31% 8% 1	570
	11th to 20th	Night	14% 7% 30% 33% 14% 2	561
	21st to end	Night	10% 12% 30% 32% 13% 2	617
June	1st to 10th	Night	5% 9% 24% 41% 18% 2	570
	11th to 20th	Night	4 8% 32% 40% 15% 2	570
	21st to end	Night	4 3 24% 40% 26% 2	570
July	1st to 10th	Night	9% 2 13% 40% 31% 5%	531
	11th to 20th	Night	5% 2 11% 36% 38% 8%	522
	21st to end	Night	7% 3 6% 35% 43% 7%	591
August	1st to 10th	Night	7% 2 9% 39% 36% 6%	537
	11th to 20th	Night	5% 2 12% 44% 34% 4	534
	21st to end	Night	6% 3 13% 41% 32% 5%	594
September	1st to 10th	Night	6% 3 18% 42% 25% 6%	540
	11th to 20th	Night	8% 5% 20% 39% 23% 5%	540
	21st to end	Night	7% 9% 25% 39% 16% 5%	540
October	1st to 10th	Night	8% 8% 32% 35% 13% 3	696
	11th to 20th	Night	4 11% 39% 30% 13% 3	720
	21st to end	Night	7% 13% 34% 30% 13% 3	792
November	1st to 10th	Night	5% 15% 36% 31% 11% 1	919
	11th to 20th	Night	7% 16% 39% 27% 9% 1	950
	21st to end	Night	8% 16% 38% 30% 8% 1	950
December	1st to 10th	Night	8% 19% 40% 25% 7% 1	950
	11th to 20th	Night	7% 22% 42% 20% 9%	950
	21st to end	Night	9% 22% 42% 21% 4 1	1045

Page generated at 2024-06-29 20:08:51. Version ac07

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