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 2024-02-20.

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	6% 10% 4 7% 5% 3 4 4 5% 6% 45%	78501
	Night	6% 10% 4 7% 5% 3 4 4 5% 7% 45%	80733
Transparency	Day	36% 7% 11% 18% 18% 10%	78226
	Night	36% 7% 12% 19% 17% 8%	80529
Seeing	Day	13% 16% 32% 28% 10% 2	14057
	Night	12% 8% 23% 35% 19% 3	24552

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	5% 18% 10% 11% 9% 3 3 4 4 4 29%	2858
	11th to 20th	Day	6% 20% 10% 16% 7% 2 3 3 3 4 25%	2860
	21st to end	Day	5% 18% 8% 10% 4 3 3 3 3 6% 36%	3146
February	1st to 10th	Day	8% 19% 7% 10% 6% 3 3 4 3 5% 32%	1710
	11th to 20th	Day	7% 16% 6% 10% 8% 3 4 4 4 5% 33%	1713
	21st to end	Day	5% 18% 7% 14% 7% 3 4 5% 5% 5% 26%	1480
March	1st to 10th	Day	6% 14% 7% 10% 6% 4 4 5% 6% 7% 31%	1928
	11th to 20th	Day	5% 12% 4 9% 6% 3 6% 6% 6% 7% 34%	1980
	21st to end	Day	9% 18% 6% 10% 5% 3 6% 4 4 6% 28%	2178
April	1st to 10th	Day	9% 14% 5% 7% 4 3 5% 5% 5% 6% 36%	2002
	11th to 20th	Day	8% 16% 5% 7% 7% 4 3 4 5% 5% 37%	2263
	21st to end	Day	7% 14% 4 6% 5% 2 3 5% 5% 8% 41%	2340
May	1st to 10th	Day	8% 9% 3 6% 5% 3 6% 7% 7% 8% 38%	2340
	11th to 20th	Day	7% 8% 3 5% 6% 3 5% 6% 7% 8% 43%	2301
	21st to end	Day	8% 8% 3 6% 6% 5% 6% 7% 6% 7% 38%	2530
June	1st to 10th	Day	5% 4 2 4 4 3 5% 5% 6% 9% 53%	2448
	11th to 20th	Day	6% 4 2 3 4 2 4 4 4 6% 60%	2520
	21st to end	Day	2 2 1 3 4 2 3 4 4 5% 70%	2396
July	1st to 10th	Day	2 2 1 3 4 3 4 5% 6% 7% 63%	2340
	11th to 20th	Day	4 3 2 3 4 3 4 5% 6% 7% 58%	2340
	21st to end	Day	5% 4 2 3 5% 3 5% 6% 7% 8% 53%	2545
August	1st to 10th	Day	4 3 2 4 5% 3 6% 5% 6% 6% 57%	2328
	11th to 20th	Day	3 4 1 4 3 2 4 4 6% 7% 63%	2299
	21st to end	Day	4 3 2 3 4 3 4 4 7% 7% 60%	2552
September	1st to 10th	Day	4 3 1 3 2 2 3 4 5% 5% 69%	2044
	11th to 20th	Day	5% 3 1 3 4 3 4 4 5% 6% 62%	1980
	21st to end	Day	7% 4 1 3 3 2 3 2 4 6% 65%	1980
October	1st to 10th	Day	9% 8% 2 4 4 2 4 4 5% 5% 52%	1886
	11th to 20th	Day	7% 8% 2 4 3 2 3 3 5% 6% 56%	1800
	21st to end	Day	5% 11% 2 5% 5% 2 4 5% 4 6% 52%	1977
November	1st to 10th	Day	8% 13% 3 6% 5% 3 4 4 4 4 44%	1674
	11th to 20th	Day	11% 11% 5% 6% 4 3 3 4 4 6% 44%	1710
	21st to end	Day	6% 12% 6% 9% 6% 3 5% 3 4 5% 41%	1553
December	1st to 10th	Day	8% 13% 6% 9% 6% 1 3 4 4 7% 39%	1520
	11th to 20th	Day	7% 13% 7% 12% 7% 4 5% 5% 6% 7% 28%	1926
	21st to end	Day	5% 13% 6% 11% 6% 4 4 5% 6% 6% 33%	3054
January	1st to 10th	Night	5% 14% 10% 14% 5% 2 3 3 4 6% 33%	4097
	11th to 20th	Night	6% 21% 8% 14% 5% 2 4 3 4 5% 27%	4110
	21st to end	Night	4 16% 7% 9% 5% 3 4 4 5% 7% 35%	4521
February	1st to 10th	Night	6% 13% 7% 10% 6% 3 5% 5% 5% 6% 33%	2470
	11th to 20th	Night	6% 15% 6% 11% 5% 2 4 3 4 6% 39%	2334
	21st to end	Night	4 13% 7% 12% 6% 3 4 5% 5% 6% 35%	1776
March	1st to 10th	Night	7% 14% 7% 10% 6% 3 5% 4 4 6% 34%	2030
	11th to 20th	Night	6% 11% 4 7% 6% 3 4 5% 7% 8% 41%	1980
	21st to end	Night	7% 16% 5% 6% 6% 2 4 5% 6% 7% 36%	2178
April	1st to 10th	Night	10% 13% 5% 5% 4 2 3 4 3 6% 44%	1957
	11th to 20th	Night	7% 11% 3 6% 5% 3 5% 5% 6% 6% 44%	1641
	21st to end	Night	8% 11% 3 5% 6% 3 4 4 4 7% 45%	1620
May	1st to 10th	Night	8% 9% 3 6% 6% 3 4 5% 7% 7% 42%	1620
	11th to 20th	Night	8% 6% 2 4 5% 2 4 5% 6% 8% 49%	1594
	21st to end	Night	8% 5% 3 6% 5% 3 5% 6% 8% 8% 42%	1746
June	1st to 10th	Night	6% 5% 3 4 4 3 4 5% 5% 7% 55%	1504
	11th to 20th	Night	4 3 1 3 3 2 3 4 5% 7% 64%	1440
	21st to end	Night	3 3 1 3 3 2 3 4 5% 8% 66%	1554
July	1st to 10th	Night	4 4 1 5% 5% 3 5% 5% 6% 6% 57%	1620
	11th to 20th	Night	4 4 2 5% 5% 4 4 5% 6% 7% 54%	1620
	21st to end	Night	4 3 2 5% 5% 3 5% 6% 7% 8% 53%	1773
August	1st to 10th	Night	4 3 1 4 4 4 4 4 6% 8% 58%	1611
	11th to 20th	Night	2 3 2 3 5% 4 5% 5% 5% 8% 58%	1602
	21st to end	Night	4 3 1 3 4 2 5% 5% 6% 7% 59%	1804
September	1st to 10th	Night	4 3 2 4 3 2 3 4 3 6% 67%	1913
	11th to 20th	Night	5% 3 1 4 3 2 3 3 5% 7% 65%	1980
	21st to end	Night	5% 5% 1 2 3 2 2 3 4 4 69%	1980
October	1st to 10th	Night	8% 6% 2 4 4 3 4 4 4 5% 57%	2072
	11th to 20th	Night	7% 7% 3 4 4 2 3 4 4 6% 58%	2160
	21st to end	Night	6% 9% 2 3 4 2 3 3 5% 7% 55%	2376
November	1st to 10th	Night	7% 9% 4 5% 4 2 4 4 6% 7% 47%	2405
	11th to 20th	Night	9% 9% 3 5% 4 3 4 4 5% 7% 46%	2470
	21st to end	Night	7% 11% 5% 7% 5% 3 4 4 4 6% 45%	2605
December	1st to 10th	Night	6% 13% 6% 7% 5% 2 4 4 5% 7% 41%	2660
	11th to 20th	Night	8% 12% 6% 8% 6% 3 5% 5% 5% 7% 35%	3271
	21st to end	Night	6% 14% 5% 12% 7% 3 4 4 5% 6% 32%	4639

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	52% 12% 13% 14% 9% 1	2859
	11th to 20th	Day	58% 9% 13% 12% 6% 1	2860
	21st to end	Day	48% 10% 18% 15% 8% 1	3146
February	1st to 10th	Day	54% 7% 13% 15% 9% 2	1710
	11th to 20th	Day	51% 8% 13% 17% 11% 1	1722
	21st to end	Day	56% 7% 12% 15% 8% 1	1480
March	1st to 10th	Day	47% 9% 14% 20% 9% 1	1928
	11th to 20th	Day	42% 8% 16% 20% 12% 2	1980
	21st to end	Day	53% 8% 15% 15% 7% 2	2178
April	1st to 10th	Day	45% 7% 12% 17% 13% 5%	2002
	11th to 20th	Day	46% 8% 12% 18% 15% 1	2266
	21st to end	Day	39% 7% 11% 24% 18% 1	2340
May	1st to 10th	Day	37% 8% 12% 22% 17% 3	2340
	11th to 20th	Day	34% 7% 13% 23% 19% 4	2304
	21st to end	Day	39% 9% 14% 20% 16% 2	2530
June	1st to 10th	Day	25% 7% 10% 21% 28% 8%	2448
	11th to 20th	Day	23% 4 9% 19% 26% 18%	2520
	21st to end	Day	16% 3 6% 13% 30% 33%	2396
July	1st to 10th	Day	18% 5% 9% 13% 24% 32%	2276
	11th to 20th	Day	21% 5% 9% 13% 24% 28%	2271
	21st to end	Day	23% 7% 10% 13% 22% 24%	2404
August	1st to 10th	Day	23% 5% 9% 18% 21% 25%	2313
	11th to 20th	Day	19% 5% 8% 14% 28% 26%	2299
	21st to end	Day	21% 4 7% 19% 30% 19%	2552
September	1st to 10th	Day	17% 5% 6% 16% 28% 28%	2044
	11th to 20th	Day	22% 5% 8% 19% 25% 20%	1980
	21st to end	Day	22% 4 7% 20% 34% 14%	1980
October	1st to 10th	Day	33% 5% 8% 20% 25% 8%	1886
	11th to 20th	Day	28% 3 11% 28% 23% 6%	1800
	21st to end	Day	31% 6% 14% 26% 20% 3	1977
November	1st to 10th	Day	38% 8% 13% 20% 17% 4	1674
	11th to 20th	Day	40% 6% 12% 26% 16% 1	1710
	21st to end	Day	44% 5% 11% 23% 14% 3	1553
December	1st to 10th	Day	44% 9% 17% 17% 9% 4	1520
	11th to 20th	Day	48% 10% 14% 18% 10%	1924
	21st to end	Day	44% 9% 15% 14% 16% 1	3054
January	1st to 10th	Night	48% 10% 13% 18% 10% 1	4097
	11th to 20th	Night	57% 9% 12% 14% 6% 2	4110
	21st to end	Night	46% 10% 20% 15% 7% 2	4521
February	1st to 10th	Night	47% 9% 15% 18% 10% 1	2470
	11th to 20th	Night	45% 6% 12% 19% 16% 2	2335
	21st to end	Night	46% 7% 14% 19% 11% 2	1776
March	1st to 10th	Night	47% 7% 13% 19% 13%	2030
	11th to 20th	Night	36% 8% 15% 24% 15% 2	1980
	21st to end	Night	43% 9% 14% 22% 9% 3	2178
April	1st to 10th	Night	40% 6% 14% 19% 15% 6%	1957
	11th to 20th	Night	34% 8% 14% 22% 19% 2	1641
	21st to end	Night	36% 7% 13% 22% 21% 1	1620
May	1st to 10th	Night	35% 8% 14% 21% 20% 2	1620
	11th to 20th	Night	28% 7% 13% 25% 20% 6%	1595
	21st to end	Night	32% 9% 16% 24% 16% 3	1746
June	1st to 10th	Night	26% 5% 10% 23% 28% 8%	1504
	11th to 20th	Night	18% 6% 9% 19% 29% 20%	1440
	21st to end	Night	15% 3 5% 11% 30% 35%	1554
July	1st to 10th	Night	23% 5% 9% 13% 19% 31%	1575
	11th to 20th	Night	25% 6% 8% 13% 20% 27%	1566
	21st to end	Night	24% 6% 11% 15% 20% 24%	1674
August	1st to 10th	Night	22% 6% 11% 17% 20% 24%	1602
	11th to 20th	Night	21% 6% 9% 13% 26% 26%	1602
	21st to end	Night	20% 5% 8% 15% 29% 22%	1804
September	1st to 10th	Night	18% 4 7% 17% 22% 32%	1913
	11th to 20th	Night	19% 5% 8% 19% 26% 23%	1980
	21st to end	Night	20% 3 6% 18% 35% 17%	1980
October	1st to 10th	Night	27% 5% 10% 22% 27% 9%	2072
	11th to 20th	Night	26% 6% 7% 27% 27% 7%	2160
	21st to end	Night	27% 5% 12% 26% 25% 4	2376
November	1st to 10th	Night	32% 7% 12% 24% 20% 5%	2405
	11th to 20th	Night	34% 7% 13% 25% 17% 3	2470
	21st to end	Night	38% 5% 12% 24% 16% 4	2605
December	1st to 10th	Night	41% 7% 16% 22% 11% 4	2660
	11th to 20th	Night	42% 11% 16% 18% 12% 1	3272
	21st to end	Night	47% 9% 16% 15% 11% 2	4639

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	26% 14% 28% 21% 11% 1	270
	11th to 20th	Day	19% 15% 31% 22% 11% 1	270
	21st to end	Day	16% 12% 28% 33% 8% 2	297
February	1st to 10th	Day	26% 16% 31% 21% 6%	270
	11th to 20th	Day	18% 21% 33% 21% 6% 1	324
	21st to end	Day	18% 22% 37% 19% 3 1	346
March	1st to 10th	Day	20% 23% 32% 17% 8% 1	420
	11th to 20th	Day	15% 21% 35% 22% 7%	420
	21st to end	Day	24% 24% 32% 19% 2	462
April	1st to 10th	Day	23% 19% 30% 22% 5% 1	420
	11th to 20th	Day	24% 23% 31% 17% 4	412
	21st to end	Day	22% 23% 25% 23% 6% 1	420
May	1st to 10th	Day	14% 23% 36% 19% 6% 1	423
	11th to 20th	Day	14% 21% 33% 23% 8% 2	448
	21st to end	Day	13% 16% 31% 27% 11% 2	485
June	1st to 10th	Day	7% 15% 36% 28% 11% 2	558
	11th to 20th	Day	10% 15% 33% 28% 13% 1	630
	21st to end	Day	3 15% 37% 34% 10% 1	506
July	1st to 10th	Day	3 10% 41% 37% 8% 2	446
	11th to 20th	Day	4 10% 42% 32% 10% 2	444
	21st to end	Day	4 4 40% 36% 13% 3	487
August	1st to 10th	Day	6% 10% 37% 33% 12% 2	447
	11th to 20th	Day	4 7% 35% 38% 13% 3	437
	21st to end	Day	5% 9% 32% 38% 13% 2	495
September	1st to 10th	Day	5% 11% 32% 33% 17% 3	450
	11th to 20th	Day	8% 15% 31% 33% 12% 1	450
	21st to end	Day	10% 14% 25% 34% 16% 1	450
October	1st to 10th	Day	14% 16% 28% 27% 14% 1	356
	11th to 20th	Day	12% 19% 21% 27% 19% 2	270
	21st to end	Day	13% 17% 33% 27% 9%	297
November	1st to 10th	Day	22% 19% 20% 29% 8% 2	270
	11th to 20th	Day	17% 13% 30% 26% 9% 4	270
	21st to end	Day	14% 14% 24% 29% 15% 3	270
December	1st to 10th	Day	19% 14% 25% 29% 11% 2	270
	11th to 20th	Day	17% 14% 33% 28% 7%	270
	21st to end	Day	25% 12% 32% 24% 6% 1	297
January	1st to 10th	Night	18% 8% 24% 30% 18% 3	760
	11th to 20th	Night	17% 8% 24% 33% 14% 4	760
	21st to end	Night	13% 10% 23% 35% 16% 3	836
February	1st to 10th	Night	17% 8% 27% 35% 11% 2	760
	11th to 20th	Night	14% 9% 29% 33% 14% 1	742
	21st to end	Night	12% 12% 31% 30% 14% 1	592
March	1st to 10th	Night	17% 10% 29% 31% 10% 3	720
	11th to 20th	Night	11% 10% 25% 35% 16% 3	720
	21st to end	Night	18% 12% 25% 33% 11% 2	792
April	1st to 10th	Night	19% 12% 25% 32% 11% 2	697
	11th to 20th	Night	14% 13% 27% 33% 11% 2	533
	21st to end	Night	14% 8% 22% 36% 19% 2	540
May	1st to 10th	Night	12% 8% 29% 34% 15% 1	540
	11th to 20th	Night	10% 6% 21% 36% 23% 3	531
	21st to end	Night	11% 7% 22% 34% 21% 4	584
June	1st to 10th	Night	9% 9% 18% 39% 23% 2	540
	11th to 20th	Night	6% 9% 22% 43% 18% 1	540
	21st to end	Night	4 4 21% 37% 30% 3	540
July	1st to 10th	Night	5% 5% 19% 33% 36% 2	525
	11th to 20th	Night	6% 3 18% 43% 28% 2	522
	21st to end	Night	4 2 11% 41% 41% 2	591
August	1st to 10th	Night	5% 3 17% 45% 28% 2	537
	11th to 20th	Night	3 2 17% 44% 31% 3	534
	21st to end	Night	5% 4 17% 47% 26% 2	594
September	1st to 10th	Night	5% 6% 15% 46% 24% 4	653
	11th to 20th	Night	7% 5% 19% 38% 25% 6%	720
	21st to end	Night	8% 5% 20% 30% 28% 8%	720
October	1st to 10th	Night	11% 6% 24% 36% 19% 4	720
	11th to 20th	Night	12% 4 21% 36% 23% 5%	720
	21st to end	Night	12% 8% 22% 35% 20% 4	792
November	1st to 10th	Night	15% 10% 20% 33% 19% 3	740
	11th to 20th	Night	16% 7% 24% 34% 15% 4	760
	21st to end	Night	14% 9% 24% 33% 16% 4	895
December	1st to 10th	Night	15% 8% 27% 34% 15% 1	950
	11th to 20th	Night	20% 9% 25% 34% 11% 2	950
	21st to end	Night	22% 12% 24% 32% 9% 1	902

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