Emigration Canyon Lookout
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Emigration Canyon Lookout clear sky chart from 2005-11-06 to 2025-04-11.

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	5% 10% 4 7% 4 4 4 3 5% 6% 49%	117541
	Night	5% 10% 4 8% 4 4 4 3 5% 6% 48%	119672
Transparency	Day	31% 8% 11% 19% 19% 12%	117306
	Night	31% 8% 12% 20% 19% 10%	119496
Seeing	Day	13% 16% 32% 27% 9% 1	15604
	Night	12% 8% 24% 35% 18% 3	26097

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 18% 9% 11% 7% 4 3 3 4 5% 31%	4098
	11th to 20th	Day	4 16% 7% 20% 6% 4 3 2 3 3 31%	4100
	21st to end	Day	3 15% 6% 10% 3 3 3 2 3 6% 46%	4510
February	1st to 10th	Day	7% 20% 6% 11% 5% 4 3 3 4 4 31%	1800
	11th to 20th	Day	7% 18% 7% 12% 6% 4 4 3 4 5% 31%	1815
	21st to end	Day	4 19% 6% 15% 6% 4 4 4 4 6% 28%	1650
March	1st to 10th	Day	3 17% 10% 11% 4 5% 4 3 4 5% 33%	4840
	11th to 20th	Day	3 11% 7% 11% 4 4 4 4 6% 7% 39%	5000
	21st to end	Day	5% 23% 7% 12% 5% 5% 5% 3 4 4 27%	5486
April	1st to 10th	Day	8% 14% 5% 8% 4 4 5% 4 6% 6% 36%	2226
	11th to 20th	Day	8% 16% 5% 8% 6% 5% 3 3 5% 5% 37%	2392
	21st to end	Day	7% 15% 3 6% 4 4 3 4 6% 7% 40%	2470
May	1st to 10th	Day	7% 17% 5% 7% 4 4 5% 5% 6% 6% 34%	4110
	11th to 20th	Day	6% 6% 2 4 4 3 4 3 5% 8% 55%	4071
	21st to end	Day	6% 8% 3 6% 4 5% 4 5% 5% 6% 47%	4477
June	1st to 10th	Day	4 4 2 5% 4 4 4 4 6% 8% 53%	2584
	11th to 20th	Day	5% 5% 2 4 4 3 3 3 4 7% 61%	2660
	21st to end	Day	2 2 1 4 3 3 3 3 4 5% 70%	2529
July	1st to 10th	Day	1 1 1 2 3 2 2 3 4 4 76%	4110
	11th to 20th	Day	2 3 1 3 3 4 4 5% 7% 9% 60%	4110
	21st to end	Day	3 3 1 3 3 3 4 4 6% 7% 64%	4454
August	1st to 10th	Day	3 3 2 4 4 4 4 3 5% 6% 63%	4092
	11th to 20th	Day	2 2 1 3 3 3 4 4 6% 7% 65%	4028
	21st to end	Day	2 2 1 2 2 2 3 3 5% 6% 71%	4473
September	1st to 10th	Day	3 3 1 3 2 2 3 3 5% 5% 69%	2157
	11th to 20th	Day	5% 4 1 3 3 4 4 4 5% 5% 62%	2090
	21st to end	Day	6% 4 1 3 2 3 3 2 4 6% 66%	2090
October	1st to 10th	Day	5% 5% 1 4 3 3 3 3 4 3 67%	3312
	11th to 20th	Day	8% 8% 1 3 2 2 4 3 4 7% 56%	3150
	21st to end	Day	6% 10% 3 6% 4 3 3 3 3 6% 54%	3423
November	1st to 10th	Day	7% 13% 3 7% 5% 3 5% 3 4 4 44%	1764
	11th to 20th	Day	10% 12% 4 6% 4 4 3 3 4 6% 43%	1800
	21st to end	Day	5% 14% 5% 10% 5% 5% 4 3 4 5% 41%	1634
December	1st to 10th	Day	5% 9% 3 8% 3 2 2 3 3 6% 55%	2620
	11th to 20th	Day	6% 14% 8% 11% 5% 5% 4 4 6% 7% 30%	3026
	21st to end	Day	7% 16% 6% 13% 6% 6% 5% 4 6% 5% 28%	4390
January	1st to 10th	Night	5% 15% 9% 15% 4 4 3 3 4 5% 34%	5867
	11th to 20th	Night	5% 18% 7% 15% 4 4 3 3 4 4 34%	5880
	21st to end	Night	3 13% 5% 8% 4 4 4 3 4 6% 48%	6468
February	1st to 10th	Night	6% 14% 6% 11% 5% 4 5% 4 5% 6% 33%	2600
	11th to 20th	Night	5% 16% 6% 12% 4 3 3 3 4 6% 38%	2467
	21st to end	Night	4 15% 5% 12% 5% 4 4 4 5% 6% 37%	1980
March	1st to 10th	Night	5% 15% 6% 11% 5% 4 4 4 5% 6% 34%	5052
	11th to 20th	Night	3 12% 5% 8% 5% 4 5% 4 7% 8% 38%	5000
	21st to end	Night	5% 19% 6% 9% 4 3 4 3 5% 5% 37%	5489
April	1st to 10th	Night	9% 14% 5% 6% 3 3 3 3 3 6% 44%	2173
	11th to 20th	Night	7% 12% 2 6% 4 4 4 4 6% 6% 44%	1738
	21st to end	Night	8% 11% 2 6% 5% 4 4 3 5% 7% 44%	1710
May	1st to 10th	Night	7% 15% 5% 7% 5% 4 4 4 6% 6% 37%	2860
	11th to 20th	Night	5% 5% 2 4 3 3 4 3 5% 7% 58%	2834
	21st to end	Night	7% 6% 2 6% 4 4 4 4 6% 8% 49%	3110
June	1st to 10th	Night	5% 5% 2 5% 4 4 4 4 5% 8% 54%	1587
	11th to 20th	Night	4 3 2 3 3 3 4 3 6% 7% 63%	1520
	21st to end	Night	2 3 1 4 2 3 3 3 5% 8% 66%	1641
July	1st to 10th	Night	2 3 1 4 3 3 3 3 3 4 72%	2860
	11th to 20th	Night	2 3 1 5% 4 5% 5% 5% 8% 9% 53%	2860
	21st to end	Night	3 3 1 5% 3 4 5% 4 6% 6% 59%	3109
August	1st to 10th	Night	3 2 1 5% 3 4 4 4 6% 8% 60%	2847
	11th to 20th	Night	3 2 2 4 4 5% 4 4 5% 6% 60%	2811
	21st to end	Night	2 2 1 3 3 3 4 3 5% 6% 70%	3194
September	1st to 10th	Night	4 3 1 4 2 3 3 3 3 6% 66%	2020
	11th to 20th	Night	5% 3 1 4 2 3 3 2 5% 7% 65%	2090
	21st to end	Night	5% 5% 1 3 2 2 2 2 4 4 70%	2090
October	1st to 10th	Night	4 4 1 3 3 3 2 2 3 4 70%	3660
	11th to 20th	Night	6% 7% 2 4 3 3 4 3 5% 6% 57%	3778
	21st to end	Night	6% 9% 2 5% 3 4 4 4 6% 7% 52%	4120
November	1st to 10th	Night	6% 10% 4 6% 4 3 3 4 6% 7% 47%	2535
	11th to 20th	Night	9% 9% 3 7% 4 4 3 3 5% 7% 45%	2600
	21st to end	Night	6% 12% 4 7% 4 3 4 3 4 6% 45%	2743
December	1st to 10th	Night	4 9% 3 6% 3 4 3 3 4 7% 55%	4570
	11th to 20th	Night	6% 13% 4 7% 4 4 5% 4 6% 6% 41%	5181
	21st to end	Night	6% 16% 5% 12% 6% 4 4 3 5% 6% 30%	6628

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	47% 13% 13% 13% 13% 1	4099
	11th to 20th	Day	51% 9% 11% 16% 9% 4	4100
	21st to end	Day	38% 8% 14% 18% 21% 2	4510
February	1st to 10th	Day	54% 7% 13% 15% 10% 2	1800
	11th to 20th	Day	52% 9% 12% 16% 10% 1	1824
	21st to end	Day	51% 8% 13% 16% 10% 2	1650
March	1st to 10th	Day	42% 13% 10% 19% 11% 5%	4840
	11th to 20th	Day	31% 15% 15% 26% 12% 1	5000
	21st to end	Day	51% 12% 17% 14% 6% 1	5486
April	1st to 10th	Day	43% 8% 13% 18% 13% 4	2226
	11th to 20th	Day	45% 8% 12% 19% 15% 1	2395
	21st to end	Day	39% 7% 11% 24% 18% 1	2470
May	1st to 10th	Day	38% 12% 12% 19% 15% 4	4110
	11th to 20th	Day	23% 6% 12% 30% 26% 3	4074
	21st to end	Day	28% 8% 13% 25% 22% 3	4477
June	1st to 10th	Day	25% 8% 11% 22% 27% 8%	2584
	11th to 20th	Day	23% 4 8% 19% 27% 18%	2660
	21st to end	Day	15% 4 6% 13% 29% 33%	2529
July	1st to 10th	Day	10% 3 5% 8% 15% 59%	4046
	11th to 20th	Day	15% 6% 8% 13% 23% 35%	4041
	21st to end	Day	16% 5% 7% 11% 26% 34%	4314
August	1st to 10th	Day	18% 5% 7% 19% 25% 26%	4078
	11th to 20th	Day	15% 6% 8% 15% 32% 25%	4067
	21st to end	Day	13% 3 6% 16% 31% 30%	4472
September	1st to 10th	Day	17% 5% 6% 16% 29% 27%	2157
	11th to 20th	Day	22% 5% 8% 18% 27% 19%	2090
	21st to end	Day	21% 4 6% 20% 34% 15%	2090
October	1st to 10th	Day	22% 4 6% 13% 36% 20%	3312
	11th to 20th	Day	27% 4 8% 28% 26% 6%	3150
	21st to end	Day	29% 6% 11% 28% 22% 4	3423
November	1st to 10th	Day	37% 8% 13% 20% 17% 4	1764
	11th to 20th	Day	39% 6% 12% 26% 16% 1	1800
	21st to end	Day	43% 5% 11% 23% 15% 3	1634
December	1st to 10th	Day	28% 7% 11% 39% 12% 3	2620
	11th to 20th	Day	43% 12% 15% 18% 11%	3024
	21st to end	Day	47% 11% 13% 14% 13% 1	4390
January	1st to 10th	Night	44% 12% 13% 16% 13% 2	5867
	11th to 20th	Night	48% 10% 10% 22% 8% 2	5880
	21st to end	Night	36% 8% 15% 19% 20% 2	6468
February	1st to 10th	Night	47% 9% 15% 18% 10% 2	2600
	11th to 20th	Night	45% 7% 12% 19% 16% 2	2468
	21st to end	Night	44% 8% 13% 20% 12% 4	1980
March	1st to 10th	Night	40% 12% 11% 18% 13% 5%	5052
	11th to 20th	Night	31% 13% 15% 25% 15% 1	5000
	21st to end	Night	40% 12% 16% 18% 13% 1	5489
April	1st to 10th	Night	37% 7% 14% 20% 16% 5%	2173
	11th to 20th	Night	34% 9% 13% 22% 20% 2	1738
	21st to end	Night	36% 8% 13% 22% 20% 1	1710
May	1st to 10th	Night	35% 12% 14% 19% 19% 2	2860
	11th to 20th	Night	19% 9% 14% 27% 25% 6%	2835
	21st to end	Night	25% 8% 13% 27% 25% 2	3110
June	1st to 10th	Night	26% 6% 11% 23% 28% 7%	1587
	11th to 20th	Night	18% 6% 9% 19% 30% 19%	1520
	21st to end	Night	15% 3 5% 11% 30% 35%	1641
July	1st to 10th	Night	14% 3 5% 8% 12% 57%	2815
	11th to 20th	Night	20% 5% 7% 11% 25% 32%	2806
	21st to end	Night	21% 5% 8% 11% 24% 30%	3011
August	1st to 10th	Night	18% 6% 8% 15% 28% 25%	2838
	11th to 20th	Night	21% 6% 8% 12% 28% 25%	2838
	21st to end	Night	13% 5% 7% 11% 32% 32%	3194
September	1st to 10th	Night	18% 5% 7% 16% 24% 31%	2020
	11th to 20th	Night	19% 5% 8% 20% 27% 22%	2090
	21st to end	Night	19% 3 6% 18% 35% 19%	2090
October	1st to 10th	Night	17% 4 7% 16% 35% 22%	3660
	11th to 20th	Night	24% 6% 7% 29% 26% 8%	3778
	21st to end	Night	26% 7% 10% 28% 26% 3	4120
November	1st to 10th	Night	31% 7% 12% 24% 21% 5%	2535
	11th to 20th	Night	33% 8% 13% 26% 17% 3	2600
	21st to end	Night	38% 5% 12% 25% 16% 4	2743
December	1st to 10th	Night	26% 7% 11% 35% 18% 2	4570
	11th to 20th	Night	35% 10% 20% 23% 11%	5182
	21st to end	Night	45% 11% 16% 16% 11% 2	6628

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	25% 16% 28% 19% 10% 1	300
	11th to 20th	Day	18% 16% 31% 22% 11% 2	300
	21st to end	Day	15% 15% 28% 32% 8% 2	330
February	1st to 10th	Day	30% 15% 30% 19% 5%	300
	11th to 20th	Day	19% 21% 33% 20% 5% 1	360
	21st to end	Day	17% 21% 36% 21% 4 1	414
March	1st to 10th	Day	20% 23% 31% 17% 8% 1	500
	11th to 20th	Day	15% 23% 35% 21% 7%	500
	21st to end	Day	23% 24% 31% 19% 2	550
April	1st to 10th	Day	21% 21% 29% 22% 6% 1	500
	11th to 20th	Day	24% 22% 31% 18% 5%	453
	21st to end	Day	21% 22% 28% 23% 6% 1	460
May	1st to 10th	Day	16% 24% 36% 18% 6% 1	463
	11th to 20th	Day	14% 21% 32% 23% 9% 2	488
	21st to end	Day	13% 16% 31% 27% 11% 2	529
June	1st to 10th	Day	7% 15% 36% 29% 11% 2	604
	11th to 20th	Day	11% 15% 34% 27% 12% 1	680
	21st to end	Day	3 17% 38% 32% 9% 1	549
July	1st to 10th	Day	3 11% 41% 34% 8% 2	486
	11th to 20th	Day	3 9% 42% 33% 11% 2	484
	21st to end	Day	4 5% 40% 36% 12% 2	531
August	1st to 10th	Day	6% 10% 37% 33% 12% 2	487
	11th to 20th	Day	4 10% 36% 36% 12% 3	477
	21st to end	Day	5% 12% 32% 36% 12% 2	539
September	1st to 10th	Day	4 11% 31% 33% 18% 3	490
	11th to 20th	Day	9% 17% 30% 32% 11% 1	490
	21st to end	Day	10% 14% 27% 33% 16% 1	490
October	1st to 10th	Day	13% 15% 28% 28% 15% 1	390
	11th to 20th	Day	13% 19% 22% 28% 17% 2	300
	21st to end	Day	15% 17% 32% 28% 9%	330
November	1st to 10th	Day	21% 19% 23% 27% 8% 2	300
	11th to 20th	Day	18% 14% 31% 25% 8% 4	300
	21st to end	Day	15% 14% 26% 29% 14% 2	300
December	1st to 10th	Day	17% 14% 24% 31% 11% 3	300
	11th to 20th	Day	18% 15% 32% 28% 7%	300
	21st to end	Day	26% 12% 32% 23% 6% 1	330
January	1st to 10th	Night	18% 8% 26% 29% 17% 3	800
	11th to 20th	Night	17% 8% 25% 33% 14% 4	800
	21st to end	Night	13% 10% 25% 34% 15% 3	880
February	1st to 10th	Night	19% 8% 27% 33% 11% 2	800
	11th to 20th	Night	15% 10% 29% 32% 14% 1	784
	21st to end	Night	13% 11% 33% 30% 13% 1	660
March	1st to 10th	Night	17% 11% 29% 30% 10% 3	800
	11th to 20th	Night	11% 11% 27% 34% 15% 2	800
	21st to end	Night	18% 13% 26% 33% 10% 2	880
April	1st to 10th	Night	18% 12% 25% 32% 11% 2	773
	11th to 20th	Night	14% 13% 27% 33% 11% 1	565
	21st to end	Night	14% 8% 23% 35% 18% 2	570
May	1st to 10th	Night	13% 9% 29% 33% 15% 1	570
	11th to 20th	Night	10% 7% 22% 36% 22% 3	561
	21st to end	Night	11% 7% 23% 35% 20% 4	617
June	1st to 10th	Night	9% 9% 18% 41% 22% 2	570
	11th to 20th	Night	6% 9% 23% 43% 17% 1	570
	21st to end	Night	4 4 23% 38% 29% 3	570
July	1st to 10th	Night	5% 5% 19% 34% 35% 2	555
	11th to 20th	Night	6% 3 17% 43% 28% 2	552
	21st to end	Night	4 3 12% 42% 39% 2	624
August	1st to 10th	Night	5% 3 17% 47% 27% 2	567
	11th to 20th	Night	3 2 20% 43% 30% 3	564
	21st to end	Night	5% 4 18% 46% 26% 2	627
September	1st to 10th	Night	5% 6% 15% 47% 24% 4	690
	11th to 20th	Night	7% 5% 21% 38% 24% 5%	760
	21st to end	Night	7% 5% 20% 32% 27% 8%	760
October	1st to 10th	Night	10% 6% 24% 38% 18% 4	760
	11th to 20th	Night	12% 4 21% 36% 22% 4	760
	21st to end	Night	12% 8% 22% 35% 19% 4	836
November	1st to 10th	Night	14% 11% 21% 33% 18% 3	780
	11th to 20th	Night	15% 7% 26% 33% 15% 4	800
	21st to end	Night	14% 10% 25% 33% 15% 4	943
December	1st to 10th	Night	14% 8% 28% 34% 15% 1	1000
	11th to 20th	Night	20% 9% 27% 33% 10% 2	1000
	21st to end	Night	22% 12% 24% 32% 9% 1	949

Page generated at 2025-04-08 07:17:29. Version ac07

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