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 2024-12-02.

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 4 3 4 4 4 6% 8% 56%	105299
	Night	2 4 2 4 3 3 3 3 5% 8% 61%	103061
Transparency	Day	22% 7% 12% 23% 24% 12%	105049
	Night	20% 6% 12% 25% 26% 10%	102901
Seeing	Day	12% 16% 31% 25% 12% 3	15506
	Night	7% 14% 34% 30% 13% 2	25578

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	3 3 1 4 3 4 6% 6% 9% 9% 52%	4430
	11th to 20th	Day	2 2 1 4 6% 8% 9% 7% 10% 10% 41%	4430
	21st to end	Day	3 4 2 5% 5% 5% 6% 5% 8% 11% 47%	4524
August	1st to 10th	Day	3 3 2 6% 6% 7% 8% 8% 11% 12% 35%	4005
	11th to 20th	Day	3 3 1 3 3 5% 5% 5% 9% 11% 53%	3726
	21st to end	Day	4 4 2 5% 4 5% 6% 6% 9% 12% 43%	4180
September	1st to 10th	Day	4 5% 1 5% 4 4 5% 5% 7% 8% 52%	2280
	11th to 20th	Day	4 3 2 4 3 3 4 3 5% 7% 63%	2260
	21st to end	Day	3 3 2 4 3 3 3 3 5% 6% 66%	2090
October	1st to 10th	Day	3 3 1 2 2 3 2 3 3 6% 72%	3203
	11th to 20th	Day	2 3 1 4 3 3 3 3 5% 8% 64%	3150
	21st to end	Day	2 3 1 2 2 2 2 2 3 6% 76%	3412
November	1st to 10th	Day	1 3 2 3 2 3 2 3 5% 7% 69%	1763
	11th to 20th	Day	3 2 4 2 2 3 2 4 8% 71%	1800
	21st to end	Day	1 4 2 5% 2 2 3 3 5% 6% 66%	1789
December	1st to 10th	Day	1 3 2 4 3 3 3 2 4 7% 68%	1528
	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	5% 3 2 5% 4 5% 5% 5% 7% 8% 52%	2540
	11th to 20th	Night	2 3 1 4 4 6% 5% 6% 10% 13% 46%	2540
	21st to end	Night	3 3 1 4 4 5% 6% 5% 7% 10% 50%	3035
August	1st to 10th	Night	4 4 2 7% 5% 7% 7% 6% 9% 10% 38%	2930
	11th to 20th	Night	3 3 1 3 4 5% 6% 6% 10% 13% 46%	3113
	21st to end	Night	3 4 2 5% 4 5% 6% 6% 10% 13% 41%	3487
September	1st to 10th	Night	4 4 2 3 3 3 5% 4 6% 9% 54%	1900
	11th to 20th	Night	5% 4 1 3 2 2 3 4 5% 7% 64%	1919
	21st to end	Night	4 4 1 3 2 2 3 3 5% 5% 65%	2090
October	1st to 10th	Night	2 3 1 2 1 2 2 3 3 5% 75%	3762
	11th to 20th	Night	2 4 1 4 3 2 3 3 5% 7% 66%	3778
	21st to end	Night	2 3 1 3 2 2 2 2 3 5% 75%	4120
November	1st to 10th	Night	1 3 1 3 2 2 2 3 4 7% 71%	2529
	11th to 20th	Night	1 3 1 3 2 2 2 2 4 6% 75%	2600
	21st to end	Night	1 5% 1 4 2 2 2 3 4 7% 68%	2609
December	1st to 10th	Night	1 3 1 4 3 3 3 3 5% 8% 67%	2687
	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	24% 8% 14% 21% 21% 12%	2660
July	1st to 10th	Day	24% 8% 13% 17% 19% 18%	4361
	11th to 20th	Day	29% 10% 16% 27% 14% 4	4355
	21st to end	Day	27% 10% 17% 20% 16% 11%	4381
August	1st to 10th	Day	36% 11% 22% 17% 8% 5%	3991
	11th to 20th	Day	24% 7% 19% 20% 18% 14%	3762
	21st to end	Day	28% 7% 20% 21% 21% 4	4179
September	1st to 10th	Day	26% 9% 11% 23% 21% 11%	2280
	11th to 20th	Day	19% 7% 10% 20% 28% 17%	2260
	21st to end	Day	19% 6% 7% 20% 35% 12%	2090
October	1st to 10th	Day	14% 5% 6% 17% 35% 23%	3203
	11th to 20th	Day	20% 4 8% 25% 33% 11%	3150
	21st to end	Day	12% 3 5% 19% 42% 19%	3412
November	1st to 10th	Day	14% 4 8% 24% 35% 16%	1763
	11th to 20th	Day	14% 4 8% 30% 32% 12%	1800
	21st to end	Day	19% 5% 7% 21% 32% 17%	1789
December	1st to 10th	Day	17% 5% 12% 31% 25% 9%	1528
	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	28% 9% 13% 18% 16% 16%	2500
	11th to 20th	Night	24% 7% 24% 30% 10% 4	2492
	21st to end	Night	24% 11% 18% 23% 19% 5%	2940
August	1st to 10th	Night	38% 11% 21% 16% 9% 4	2921
	11th to 20th	Night	27% 8% 25% 16% 16% 8%	3143
	21st to end	Night	29% 8% 22% 23% 15% 3	3487
September	1st to 10th	Night	24% 8% 14% 24% 21% 9%	1900
	11th to 20th	Night	18% 7% 11% 20% 26% 18%	1919
	21st to end	Night	19% 6% 9% 21% 35% 10%	2090
October	1st to 10th	Night	14% 4 8% 22% 35% 18%	3762
	11th to 20th	Night	20% 3 12% 24% 31% 11%	3778
	21st to end	Night	15% 3 5% 24% 39% 15%	4120
November	1st to 10th	Night	13% 4 8% 26% 33% 16%	2529
	11th to 20th	Night	13% 3 7% 31% 33% 13%	2600
	21st to end	Night	17% 4 9% 23% 35% 13%	2609
December	1st to 10th	Night	16% 6% 12% 32% 25% 9%	2687
	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% 30% 18% 4	680
July	1st to 10th	Day	6% 5% 25% 37% 20% 7%	671
	11th to 20th	Day	4 4 17% 37% 30% 9%	668
	21st to end	Day	5% 3 16% 36% 29% 10%	575
August	1st to 10th	Day	5% 5% 24% 35% 22% 9%	487
	11th to 20th	Day	6% 4 29% 33% 23% 5%	477
	21st to end	Day	6% 6% 25% 39% 19% 5%	539
September	1st to 10th	Day	6% 9% 26% 33% 19% 6%	490
	11th to 20th	Day	5% 13% 37% 29% 13% 3	470
	21st to end	Day	8% 9% 28% 31% 17% 6%	300
October	1st to 10th	Day	11% 14% 27% 27% 16% 6%	300
	11th to 20th	Day	11% 20% 35% 19% 10% 4	300
	21st to end	Day	12% 18% 39% 18% 10% 2	330
November	1st to 10th	Day	14% 22% 34% 23% 7% 1	300
	11th to 20th	Day	13% 20% 34% 21% 10% 1	300
	21st to end	Day	10% 20% 35% 27% 5% 1	300
December	1st to 10th	Day	14% 27% 32% 19% 8% 1	273
	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	8% 3 14% 40% 30% 5%	555
	11th to 20th	Night	5% 2 11% 37% 39% 7%	552
	21st to end	Night	7% 2 6% 37% 42% 6%	624
August	1st to 10th	Night	7% 2 10% 40% 37% 5%	567
	11th to 20th	Night	5% 2 12% 45% 33% 3	564
	21st to end	Night	6% 3 13% 42% 31% 5%	627
September	1st to 10th	Night	5% 3 17% 43% 26% 6%	570
	11th to 20th	Night	8% 5% 22% 38% 22% 4	570
	21st to end	Night	7% 8% 25% 39% 17% 4	570
October	1st to 10th	Night	8% 8% 31% 38% 13% 3	735
	11th to 20th	Night	4 10% 38% 31% 14% 3	760
	21st to end	Night	7% 13% 36% 30% 12% 3	836
November	1st to 10th	Night	5% 15% 38% 31% 10% 1	969
	11th to 20th	Night	7% 16% 41% 27% 9% 1	1000
	21st to end	Night	8% 15% 40% 29% 7% 1	1000
December	1st to 10th	Night	8% 19% 40% 25% 7% 1	960
	11th to 20th	Night	7% 22% 42% 20% 9%	950
	21st to end	Night	9% 22% 42% 21% 4 1	1045

Page generated at 2024-11-29 08:43:07. Version ac07

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