Umiujaq
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Umiujaq clear sky chart from 2005-11-06 to 2024-12-06.

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	17% 15% 5% 11% 7% 6% 6% 4 5% 5% 18%	102718
	Night	14% 16% 6% 14% 9% 7% 7% 5% 5% 4 14%	97162
Transparency	Day	68% 3 10% 15% 4	105951
	Night	72% 3 8% 12% 5%	102020
Seeing	Day	25% 7% 22% 26% 15% 6%	16804
	Night	22% 7% 21% 28% 17% 5%	24749

By Month

Percentage Cloud Cover NE (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	6% 14% 6% 23% 13% 14% 11% 3 3 3 4	1898
	11th to 20th	Day	4 17% 6% 13% 13% 17% 15% 6% 5% 3 3	1997
	21st to end	Day	3 10% 6% 14% 8% 11% 14% 9% 10% 4 11%	2431
February	1st to 10th	Day	4 9% 4 12% 10% 13% 15% 14% 9% 4 6%	1433
	11th to 20th	Day	3 8% 4 10% 11% 14% 13% 11% 9% 6% 11%	1607
	21st to end	Day	4 9% 4 11% 9% 9% 13% 10% 12% 7% 11%	1413
March	1st to 10th	Day	4 12% 6% 17% 12% 8% 13% 10% 7% 3 7%	3077
	11th to 20th	Day	4 15% 7% 16% 10% 10% 7% 8% 6% 4 12%	3416
	21st to end	Day	9% 15% 5% 13% 8% 9% 11% 6% 4 5% 16%	4038
April	1st to 10th	Day	10% 15% 4 12% 9% 10% 9% 4 4 4 18%	2286
	11th to 20th	Day	9% 11% 4 12% 10% 10% 8% 4 5% 6% 21%	2520
	21st to end	Day	10% 13% 5% 12% 11% 7% 6% 4 4 6% 22%	2660
May	1st to 10th	Day	16% 11% 4 12% 7% 5% 5% 4 6% 7% 22%	4441
	11th to 20th	Day	15% 17% 7% 15% 6% 5% 4 3 4 5% 18%	4968
	21st to end	Day	10% 11% 5% 9% 5% 4 4 4 5% 7% 35%	5533
June	1st to 10th	Day	12% 11% 7% 10% 6% 5% 5% 4 5% 6% 29%	3040
	11th to 20th	Day	18% 12% 4 8% 5% 4 4 5% 6% 6% 29%	3040
	21st to end	Day	21% 11% 4 9% 6% 5% 4 4 6% 6% 24%	3040
July	1st to 10th	Day	24% 14% 5% 8% 5% 5% 5% 4 6% 6% 18%	5080
	11th to 20th	Day	23% 15% 4 9% 6% 5% 5% 3 5% 6% 21%	5080
	21st to end	Day	21% 16% 3 9% 5% 4 4 4 5% 5% 24%	5300
August	1st to 10th	Day	39% 14% 3 6% 4 4 3 2 2 4 18%	4627
	11th to 20th	Day	24% 11% 3 7% 4 3 3 3 4 8% 32%	4359
	21st to end	Day	28% 11% 3 7% 4 4 4 3 5% 7% 24%	4644
September	1st to 10th	Day	32% 16% 4 8% 3 4 5% 3 5% 5% 14%	2280
	11th to 20th	Day	29% 19% 4 10% 5% 4 3 3 3 4 17%	2280
	21st to end	Day	32% 22% 4 8% 4 4 3 3 5% 4 12%	2001
October	1st to 10th	Day	28% 24% 5% 8% 5% 4 3 3 3 3 14%	1900
	11th to 20th	Day	22% 23% 6% 10% 6% 4 4 3 4 4 14%	1793
	21st to end	Day	21% 26% 8% 12% 5% 3 3 3 3 4 12%	1717
November	1st to 10th	Day	18% 27% 9% 14% 6% 4 4 3 2 4 9%	1551
	11th to 20th	Day	17% 28% 10% 14% 6% 5% 3 2 3 3 8%	1375
	21st to end	Day	11% 23% 11% 22% 8% 5% 4 3 2 2 10%	1200
December	1st to 10th	Day	9% 18% 11% 23% 12% 6% 3 3 3 4 7%	1170
	11th to 20th	Day	6% 14% 7% 23% 16% 11% 6% 4 3 3 6%	1433
	21st to end	Day	7% 17% 6% 22% 14% 9% 8% 3 2 3 9%	2090
January	1st to 10th	Night	5% 12% 6% 25% 15% 13% 10% 4 3 2 3	5067
	11th to 20th	Night	5% 15% 6% 16% 13% 15% 11% 6% 5% 3 5%	4980
	21st to end	Night	4 10% 6% 17% 10% 10% 11% 7% 9% 4 12%	5236
February	1st to 10th	Night	4 10% 4 12% 11% 14% 14% 11% 12% 3 5%	2746
	11th to 20th	Night	2 9% 4 12% 10% 13% 13% 10% 12% 5% 8%	2455
	21st to end	Night	4 10% 5% 14% 9% 10% 14% 8% 10% 5% 11%	2041
March	1st to 10th	Night	5% 8% 5% 15% 12% 12% 11% 10% 8% 4 10%	3762
	11th to 20th	Night	5% 16% 8% 17% 9% 7% 8% 7% 6% 5% 13%	3526
	21st to end	Night	10% 13% 5% 12% 8% 10% 11% 7% 5% 4 14%	3594
April	1st to 10th	Night	11% 15% 4 11% 7% 7% 10% 4 6% 6% 19%	1900
	11th to 20th	Night	8% 12% 6% 13% 10% 9% 7% 3 4 6% 23%	1619
	21st to end	Night	10% 15% 4 11% 10% 7% 3 3 4 6% 25%	1520
May	1st to 10th	Night	15% 14% 4 11% 7% 6% 6% 4 6% 6% 21%	2497
	11th to 20th	Night	16% 17% 7% 16% 6% 4 5% 3 5% 7% 16%	1944
	21st to end	Night	12% 11% 5% 10% 5% 3 4 3 5% 5% 37%	2065
June	1st to 10th	Night	13% 15% 7% 9% 4 2 3 3 4 7% 33%	1140
	11th to 20th	Night	18% 11% 4 8% 5% 4 4 3 5% 6% 31%	1140
	21st to end	Night	19% 13% 5% 10% 5% 6% 4 3 5% 4 26%	1140
July	1st to 10th	Night	25% 14% 5% 9% 4 3 3 3 4 5% 24%	1900
	11th to 20th	Night	23% 16% 5% 9% 5% 5% 4 3 4 6% 20%	1900
	21st to end	Night	21% 16% 3 8% 5% 4 4 3 5% 6% 25%	2265
August	1st to 10th	Night	38% 17% 3 6% 3 3 3 2 4 3 17%	2307
	11th to 20th	Night	23% 10% 3 6% 4 4 4 4 6% 8% 29%	2470
	21st to end	Night	29% 10% 3 6% 3 3 3 4 5% 7% 27%	2984
September	1st to 10th	Night	35% 17% 3 8% 4 3 3 3 3 5% 16%	1893
	11th to 20th	Night	30% 20% 4 9% 4 4 3 2 3 5% 15%	1900
	21st to end	Night	28% 24% 4 7% 4 3 3 3 4 5% 14%	2176
October	1st to 10th	Night	31% 23% 4 8% 4 3 3 3 3 4 13%	2280
	11th to 20th	Night	24% 26% 6% 10% 5% 3 3 2 4 4 14%	2386
	21st to end	Night	23% 27% 7% 11% 5% 5% 3 2 3 3 11%	2878
November	1st to 10th	Night	20% 27% 8% 13% 7% 4 4 3 3 3 8%	2747
	11th to 20th	Night	16% 28% 9% 15% 7% 5% 4 2 3 3 7%	3020
	21st to end	Night	10% 23% 10% 20% 8% 5% 6% 3 4 3 9%	3200
December	1st to 10th	Night	9% 19% 9% 26% 13% 6% 4 2 3 2 6%	3127
	11th to 20th	Night	7% 15% 7% 22% 16% 7% 5% 4 3 4 10%	3769
	21st to end	Night	9% 14% 6% 22% 12% 8% 8% 4 4 4 9%	5588

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	86% 2 5% 6%	1899
	11th to 20th	Day	83% 4 6% 6% 2	1997
	21st to end	Day	68% 4 1 13% 13%	2431
February	1st to 10th	Day	65% 9% 7% 14% 5%	1433
	11th to 20th	Day	64% 6% 8% 16% 7%	1616
	21st to end	Day	60% 6% 8% 14% 12%	1413
March	1st to 10th	Day	76% 5% 6% 10% 4	3080
	11th to 20th	Day	72% 3 7% 14% 5%	3416
	21st to end	Day	72% 2 4 16% 6%	4038
April	1st to 10th	Day	70% 3 5% 14% 6% 1	2286
	11th to 20th	Day	65% 2 7% 19% 6% 1	2520
	21st to end	Day	66% 3 9% 17% 6%	2660
May	1st to 10th	Day	63% 2 11% 20% 3	4455
	11th to 20th	Day	70% 1 8% 16% 4	4972
	21st to end	Day	50% 2 7% 27% 14%	5533
June	1st to 10th	Day	56% 2 10% 23% 9%	3040
	11th to 20th	Day	54% 3 10% 22% 11%	3040
	21st to end	Day	59% 4 10% 21% 6%	3040
July	1st to 10th	Day	64% 2 13% 19% 2	5001
	11th to 20th	Day	64% 3 10% 19% 3	4993
	21st to end	Day	62% 2 22% 11% 3	5132
August	1st to 10th	Day	73% 3 11% 13% 1	4611
	11th to 20th	Day	53% 1 16% 27% 2	4401
	21st to end	Day	61% 3 12% 22% 3	4644
September	1st to 10th	Day	74% 3 11% 11% 1	2280
	11th to 20th	Day	74% 2 10% 12% 1	2280
	21st to end	Day	78% 2 11% 9% 1	2001
October	1st to 10th	Day	68% 2 17% 12% 1	3160
	11th to 20th	Day	76% 3 13% 7% 2	2957
	21st to end	Day	83% 2 8% 6% 1	2803
November	1st to 10th	Day	82% 2 6% 9% 1	1551
	11th to 20th	Day	82% 2 5% 9% 1	1375
	21st to end	Day	82% 3 5% 8% 1 1	1200
December	1st to 10th	Day	80% 2 9% 7% 2	1170
	11th to 20th	Day	82% 2 5% 6% 5%	1433
	21st to end	Day	82% 3 4 8% 3	2090
January	1st to 10th	Night	85% 3 3 5% 3	5067
	11th to 20th	Night	81% 4 8% 6% 1	4980
	21st to end	Night	69% 4 2 13% 11% 2	5236
February	1st to 10th	Night	66% 9% 7% 14% 5%	2746
	11th to 20th	Night	62% 7% 9% 16% 6%	2457
	21st to end	Night	64% 6% 7% 15% 8%	2041
March	1st to 10th	Night	71% 3 8% 13% 5%	3772
	11th to 20th	Night	70% 3 6% 15% 7%	3527
	21st to end	Night	71% 3 4 14% 7%	3594
April	1st to 10th	Night	65% 4 4 17% 9% 1	1900
	11th to 20th	Night	64% 2 4 19% 9% 1	1619
	21st to end	Night	62% 2 8% 19% 8% 1	1520
May	1st to 10th	Night	64% 1 7% 24% 4	2503
	11th to 20th	Night	71% 1 8% 15% 4	1945
	21st to end	Night	50% 2 7% 23% 18%	2066
June	1st to 10th	Night	53% 2 9% 24% 11% 1	1140
	11th to 20th	Night	55% 3 7% 23% 11%	1140
	21st to end	Night	61% 3 8% 20% 7% 1	1140
July	1st to 10th	Night	63% 2 13% 16% 5%	1870
	11th to 20th	Night	66% 3 10% 18% 2	1864
	21st to end	Night	62% 2 22% 11% 3	2193
August	1st to 10th	Night	72% 3 12% 11% 2	2299
	11th to 20th	Night	56% 2 12% 27% 3	2494
	21st to end	Night	59% 3 16% 18% 4	2984
September	1st to 10th	Night	73% 3 11% 11% 2	1893
	11th to 20th	Night	74% 2 11% 12% 1	1900
	21st to end	Night	75% 3 11% 9% 2	2176
October	1st to 10th	Night	70% 2 18% 9% 1	3800
	11th to 20th	Night	77% 3 9% 8% 2	3961
	21st to end	Night	79% 2 8% 10% 1 1	4742
November	1st to 10th	Night	82% 3 5% 8% 2	2747
	11th to 20th	Night	84% 2 5% 6% 1	3020
	21st to end	Night	79% 3 6% 10% 1 1	3200
December	1st to 10th	Night	84% 2 6% 6% 2	3127
	11th to 20th	Night	77% 3 6% 7% 6% 1	3769
	21st to end	Night	79% 3 4 9% 6%	5588

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	11% 9% 29% 29% 17% 4	180
	11th to 20th	Day	12% 11% 29% 28% 15% 4	180
	21st to end	Day	8% 8% 31% 27% 18% 9%	198
February	1st to 10th	Day	7% 5% 31% 33% 17% 7%	180
	11th to 20th	Day	3 6% 30% 36% 15% 10%	243
	21st to end	Day	8% 8% 32% 37% 11% 5%	225
March	1st to 10th	Day	9% 7% 23% 28% 22% 9%	432
	11th to 20th	Day	11% 6% 28% 32% 17% 6%	460
	21st to end	Day	15% 10% 25% 28% 13% 9%	506
April	1st to 10th	Day	17% 3 21% 29% 23% 7%	460
	11th to 20th	Day	17% 8% 19% 28% 17% 12%	452
	21st to end	Day	16% 6% 27% 26% 18% 8%	460
May	1st to 10th	Day	21% 7% 21% 25% 19% 8%	465
	11th to 20th	Day	21% 9% 23% 27% 16% 4	823
	21st to end	Day	23% 6% 25% 30% 13% 3	940
June	1st to 10th	Day	19% 5% 27% 25% 16% 7%	870
	11th to 20th	Day	24% 6% 24% 28% 14% 5%	870
	21st to end	Day	28% 4 20% 30% 15% 3	870
July	1st to 10th	Day	27% 6% 16% 30% 15% 5%	856
	11th to 20th	Day	33% 6% 18% 26% 13% 3	852
	21st to end	Day	30% 5% 15% 27% 17% 7%	825
August	1st to 10th	Day	41% 4 10% 21% 17% 6%	613
	11th to 20th	Day	36% 3 14% 22% 19% 8%	479
	21st to end	Day	37% 5% 17% 21% 13% 7%	539
September	1st to 10th	Day	42% 8% 19% 19% 8% 4	490
	11th to 20th	Day	41% 9% 19% 18% 11% 2	490
	21st to end	Day	44% 7% 19% 20% 7% 3	490
October	1st to 10th	Day	39% 14% 22% 16% 8% 2	490
	11th to 20th	Day	32% 8% 23% 21% 13% 2	433
	21st to end	Day	28% 13% 23% 19% 11% 7%	265
November	1st to 10th	Day	28% 8% 21% 26% 14% 4	200
	11th to 20th	Day	26% 12% 20% 25% 12% 7%	200
	21st to end	Day	14% 8% 26% 32% 17% 4	200
December	1st to 10th	Day	15% 11% 23% 31% 15% 5%	190
	11th to 20th	Day	17% 9% 21% 32% 16% 6%	180
	21st to end	Day	15% 9% 28% 26% 14% 9%	198
January	1st to 10th	Night	13% 7% 24% 33% 16% 7%	1040
	11th to 20th	Night	11% 7% 25% 33% 19% 5%	1011
	21st to end	Night	8% 6% 22% 34% 23% 7%	1045
February	1st to 10th	Night	7% 5% 24% 34% 22% 8%	846
	11th to 20th	Night	5% 4 22% 32% 25% 12%	743
	21st to end	Night	8% 7% 23% 32% 22% 7%	628
March	1st to 10th	Night	10% 5% 21% 30% 24% 10%	760
	11th to 20th	Night	10% 7% 26% 32% 19% 6%	760
	21st to end	Night	13% 6% 25% 32% 18% 6%	836
April	1st to 10th	Night	17% 6% 23% 27% 20% 7%	760
	11th to 20th	Night	13% 6% 18% 34% 21% 8%	495
	21st to end	Night	16% 8% 23% 36% 15% 3	380
May	1st to 10th	Night	26% 4 22% 26% 18% 4	380
	11th to 20th	Night	25% 5% 22% 30% 15% 3	374
	21st to end	Night	21% 7% 23% 33% 14% 1	411
June	1st to 10th	Night	22% 4 22% 28% 20% 5%	380
	11th to 20th	Night	20% 6% 18% 35% 17% 4	380
	21st to end	Night	24% 6% 15% 35% 18% 2	380
July	1st to 10th	Night	30% 5% 13% 30% 20% 3	370
	11th to 20th	Night	32% 5% 17% 30% 14% 2	368
	21st to end	Night	30% 7% 8% 25% 25% 4	416
August	1st to 10th	Night	40% 3 8% 23% 23% 3	378
	11th to 20th	Night	35% 3 9% 26% 23% 3	376
	21st to end	Night	41% 3 12% 22% 15% 6%	539
September	1st to 10th	Night	45% 7% 15% 20% 10% 3	753
	11th to 20th	Night	41% 7% 16% 24% 11% 1	760
	21st to end	Night	42% 10% 16% 18% 12% 1	760
October	1st to 10th	Night	44% 10% 20% 16% 9% 1	760
	11th to 20th	Night	38% 10% 17% 21% 13% 1	760
	21st to end	Night	35% 9% 19% 21% 14% 3	836
November	1st to 10th	Night	32% 9% 20% 24% 12% 5%	787
	11th to 20th	Night	24% 11% 23% 25% 14% 2	920
	21st to end	Night	16% 10% 26% 30% 14% 3	1100
December	1st to 10th	Night	15% 11% 25% 31% 16% 2	1073
	11th to 20th	Night	14% 11% 23% 31% 18% 4	1040
	21st to end	Night	11% 8% 27% 31% 18% 5%	1144

Page generated at 2024-12-03 06:45:10. Version ac07

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