Igloolik
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Igloolik clear sky chart from 2005-11-06 to 2024-11-25.

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	10% 10% 4 11% 7% 6% 6% 5% 7% 8% 27%	111396
	Night	5% 9% 5% 13% 10% 9% 9% 6% 9% 9% 17%	102570
Transparency	Day	51% 8% 17% 19% 4	110954
	Night	57% 8% 16% 16% 4	102638
Seeing	Day	14% 2 10% 23% 31% 20%	19133
	Night	9% 2 11% 25% 34% 19%	23222

By Month

Percentage Cloud Cover NW (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	11th to 20th	Day	1 3 2 8% 15% 17% 7% 9% 12% 8% 18%	100
	21st to end	Day	2 1 7% 9% 11% 7% 11% 17% 19% 16%	932
February	1st to 10th	Day	1 4 3 10% 7% 11% 10% 11% 13% 15% 16%	891
	11th to 20th	Day	3 2 7% 12% 9% 12% 10% 12% 15% 19%	1194
	21st to end	Day	4 2 10% 8% 10% 10% 6% 10% 18% 21%	1191
March	1st to 10th	Day	1 5% 3 11% 10% 9% 8% 7% 13% 10% 22%	2823
	11th to 20th	Day	1 4 4 13% 12% 10% 9% 6% 11% 10% 19%	3375
	21st to end	Day	1 7% 4 11% 8% 7% 7% 8% 10% 13% 24%	4164
April	1st to 10th	Day	3 11% 5% 9% 6% 7% 6% 6% 7% 10% 30%	2489
	11th to 20th	Day	3 7% 4 9% 9% 10% 9% 6% 7% 8% 28%	2818
	21st to end	Day	4 12% 5% 14% 9% 9% 8% 5% 6% 6% 24%	3121
May	1st to 10th	Day	5% 10% 5% 12% 10% 7% 6% 4 6% 7% 28%	5713
	11th to 20th	Day	3 8% 5% 17% 12% 7% 7% 4 7% 7% 22%	6298
	21st to end	Day	7% 13% 8% 17% 7% 6% 5% 4 6% 7% 21%	8205
June	1st to 10th	Day	12% 14% 5% 9% 6% 5% 5% 5% 6% 7% 26%	4560
	11th to 20th	Day	15% 13% 4 10% 5% 5% 4 4 6% 6% 28%	4560
	21st to end	Day	14% 10% 4 7% 6% 4 5% 4 6% 8% 31%	4560
July	1st to 10th	Day	19% 9% 3 7% 5% 5% 5% 5% 6% 8% 29%	7600
	11th to 20th	Day	12% 7% 2 6% 5% 4 5% 4 6% 8% 39%	7600
	21st to end	Day	14% 9% 3 6% 5% 4 5% 4 6% 7% 37%	7147
August	1st to 10th	Day	10% 5% 2 6% 4 5% 6% 5% 8% 9% 39%	5764
	11th to 20th	Day	10% 8% 3 8% 5% 5% 5% 4 6% 6% 41%	5208
	21st to end	Day	15% 8% 3 8% 4 5% 5% 4 6% 7% 35%	5236
September	1st to 10th	Day	15% 9% 4 8% 5% 5% 4 3 5% 8% 35%	2527
	11th to 20th	Day	14% 17% 7% 13% 6% 4 5% 4 6% 6% 18%	2295
	21st to end	Day	20% 16% 8% 14% 5% 4 3 2 3 5% 19%	2026
October	1st to 10th	Day	14% 24% 10% 19% 5% 4 3 2 3 3 13%	2941
	11th to 20th	Day	14% 24% 10% 20% 7% 4 4 2 4 3 8%	2444
	21st to end	Day	5% 18% 7% 20% 12% 9% 6% 4 4 4 10%	2153
November	1st to 10th	Day	2 9% 4 14% 14% 17% 10% 6% 6% 5% 13%	872
	11th to 20th	Day	8% 13% 8% 16% 10% 10% 11% 6% 5% 5% 8%	534
	21st to end	Day	7% 20% 4 15% 18% 2 9% 2 5% 7% 11%	55
January	1st to 10th	Night	1 5% 3 8% 9% 12% 12% 10% 11% 11% 18%	7585
	11th to 20th	Night	1 6% 4 13% 11% 10% 8% 7% 9% 12% 19%	7178
	21st to end	Night	2 1 5% 7% 11% 13% 11% 17% 17% 16%	6733
February	1st to 10th	Night	1 4 2 9% 8% 11% 12% 9% 14% 12% 16%	3289
	11th to 20th	Night	1 3 2 8% 10% 9% 11% 10% 14% 15% 18%	2873
	21st to end	Night	1 3 2 9% 10% 8% 11% 8% 12% 14% 21%	2260
March	1st to 10th	Night	1 5% 3 11% 12% 10% 9% 7% 10% 10% 21%	4028
	11th to 20th	Night	1 4 4 14% 11% 10% 9% 7% 11% 11% 18%	3584
	21st to end	Night	1 5% 3 9% 8% 7% 9% 7% 11% 13% 27%	3497
April	1st to 10th	Night	3 10% 5% 11% 6% 5% 7% 6% 7% 11% 29%	1690
	11th to 20th	Night	4 8% 3 8% 8% 12% 11% 6% 7% 7% 25%	1314
	21st to end	Night	6% 10% 4 15% 11% 9% 8% 4 4 7% 21%	1058
May	1st to 10th	Night	6% 11% 5% 16% 11% 10% 6% 4 5% 7% 18%	1261
	11th to 20th	Night	4 8% 4 19% 13% 7% 7% 5% 5% 5% 22%	598
	21st to end	Night	25% 25% 25% 25%	4
July	21st to end	Night	10% 13% 3 10% 6% 7% 5% 3 3 9% 30%	493
	August	1st to 10th	Night	11% 7% 4 7% 5% 5% 5% 4 6% 9% 39%	1166
11th to 20th		Night	11% 9% 3 10% 6% 5% 4 3 5% 7% 37%	1639
21st to end		Night	17% 9% 3 7% 4 4 4 2 5% 8% 37%	2431
September	1st to 10th	Night	14% 14% 4 9% 6% 5% 3 3 5% 6% 32%	1653
	11th to 20th	Night	13% 19% 8% 10% 6% 6% 4 3 5% 6% 18%	1863
	21st to end	Night	19% 18% 9% 15% 5% 4 4 3 3 4 17%	2155
October	1st to 10th	Night	17% 23% 10% 20% 5% 4 3 2 3 3 11%	4017
	11th to 20th	Night	16% 22% 12% 19% 7% 4 3 2 3 3 10%	4475
	21st to end	Night	6% 15% 7% 25% 12% 10% 5% 3 4 4 8%	5413
November	1st to 10th	Night	1 6% 4 14% 15% 18% 10% 5% 5% 6% 13%	3425
	11th to 20th	Night	7% 13% 7% 18% 12% 10% 10% 6% 5% 4 9%	3867
	21st to end	Night	5% 14% 7% 13% 10% 10% 10% 6% 8% 8% 10%	4426
December	1st to 10th	Night	1 9% 5% 18% 13% 11% 9% 9% 7% 7% 10%	4560
	11th to 20th	Night	2 7% 4 11% 10% 10% 11% 7% 13% 12% 13%	5675
	21st to end	Night	1 6% 5% 16% 12% 12% 9% 6% 8% 9% 16%	8360

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	11th to 20th	Day	55% 7% 27% 7% 4	100
	21st to end	Day	36% 9% 12% 28% 15%	932
February	1st to 10th	Day	44% 12% 20% 21% 2	891
	11th to 20th	Day	42% 10% 21% 18% 9%	1200
	21st to end	Day	41% 7% 21% 18% 13%	1191
March	1st to 10th	Day	46% 8% 15% 21% 10%	2823
	11th to 20th	Day	52% 8% 13% 20% 6%	3377
	21st to end	Day	47% 7% 13% 24% 9%	4164
April	1st to 10th	Day	48% 7% 12% 21% 11% 1	2489
	11th to 20th	Day	49% 8% 10% 24% 8%	2818
	21st to end	Day	58% 7% 9% 17% 9%	3121
May	1st to 10th	Day	52% 8% 11% 19% 10%	5713
	11th to 20th	Day	55% 9% 12% 16% 7%	6302
	21st to end	Day	58% 12% 13% 14% 2	8206
June	1st to 10th	Day	54% 9% 13% 21% 2	4560
	11th to 20th	Day	55% 7% 14% 22% 2	4560
	21st to end	Day	49% 9% 19% 21% 3	4560
July	1st to 10th	Day	51% 8% 18% 20% 2	7481
	11th to 20th	Day	40% 8% 21% 28% 3	7465
	21st to end	Day	43% 8% 18% 27% 4	6918
August	1st to 10th	Day	38% 11% 31% 19% 2	5742
	11th to 20th	Day	42% 7% 23% 25% 3	5259
	21st to end	Day	46% 7% 27% 19% 1	5235
September	1st to 10th	Day	48% 10% 27% 14% 1	2527
	11th to 20th	Day	65% 9% 16% 10%	2295
	21st to end	Day	68% 7% 12% 12% 1	2026
October	1st to 10th	Day	76% 5% 9% 10% 1	2941
	11th to 20th	Day	81% 5% 10% 3 1	2444
	21st to end	Day	73% 9% 12% 5% 2	2153
November	1st to 10th	Day	62% 12% 16% 8%	872
	11th to 20th	Day	72% 5% 12% 9% 2	534
	21st to end	Day	71% 5% 9% 15%	55
January	1st to 10th	Night	48% 10% 20% 20% 2	7585
	11th to 20th	Night	54% 8% 21% 15% 2	7244
	21st to end	Night	37% 9% 16% 25% 12%	6733
February	1st to 10th	Night	47% 9% 21% 20% 3	3289
	11th to 20th	Night	43% 9% 20% 20% 7%	2877
	21st to end	Night	43% 8% 19% 19% 10% 1	2260
March	1st to 10th	Night	51% 6% 12% 24% 6%	4028
	11th to 20th	Night	51% 8% 13% 20% 6% 1	3584
	21st to end	Night	42% 7% 17% 26% 8%	3497
April	1st to 10th	Night	46% 6% 15% 24% 9% 1	1690
	11th to 20th	Night	52% 8% 8% 22% 10%	1314
	21st to end	Night	60% 6% 8% 19% 7% 1	1058
May	1st to 10th	Night	58% 11% 9% 15% 6%	1261
	11th to 20th	Night	59% 6% 11% 14% 10%	598
	21st to end	Night	75% 25%	4
July	21st to end	Night	50% 7% 16% 24% 3	479
	August	1st to 10th	Night	42% 7% 29% 21% 2	1163
11th to 20th		Night	48% 6% 20% 21% 4	1654
21st to end		Night	45% 6% 30% 19%	2431
September	1st to 10th	Night	53% 8% 25% 12% 1	1653
	11th to 20th	Night	65% 8% 15% 11%	1863
	21st to end	Night	72% 6% 10% 11% 1	2155
October	1st to 10th	Night	78% 6% 8% 8%	4017
	11th to 20th	Night	80% 4 10% 5% 1	4475
	21st to end	Night	75% 9% 10% 5% 1	5413
November	1st to 10th	Night	63% 9% 17% 10% 1	3425
	11th to 20th	Night	71% 6% 14% 8% 1	3867
	21st to end	Night	66% 7% 13% 13% 1	4426
December	1st to 10th	Night	65% 10% 12% 11% 2	4560
	11th to 20th	Night	54% 8% 19% 18% 2	5675
	21st to end	Night	59% 7% 12% 15% 7% 1	8360

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	21st to end	Day	1 8% 29% 34% 28%	90
	February	1st to 10th	Day	1 5% 25% 42% 26%	153
11th to 20th		Day	1 6% 18% 36% 41%	180
21st to end		Day	1 4 24% 37% 35%	195
March	1st to 10th	Day	2 2 12% 23% 33% 27%	270
	11th to 20th	Day	2 9% 22% 33% 34%	396
	21st to end	Day	2 1 9% 24% 35% 30%	506
April	1st to 10th	Day	8% 3 8% 22% 30% 29%	460
	11th to 20th	Day	5% 1 7% 21% 36% 31%	640
	21st to end	Day	8% 3 12% 25% 30% 23%	807
May	1st to 10th	Day	10% 2 9% 23% 32% 23%	843
	11th to 20th	Day	10% 2 12% 27% 30% 18%	941
	21st to end	Day	12% 2 9% 19% 35% 23%	1347
June	1st to 10th	Day	15% 2 8% 23% 30% 21%	1250
	11th to 20th	Day	19% 2 11% 24% 27% 18%	1250
	21st to end	Day	17% 2 8% 27% 32% 14%	1250
July	1st to 10th	Day	12% 1 10% 24% 34% 19%	1226
	11th to 20th	Day	19% 2 9% 24% 30% 15%	1220
	21st to end	Day	17% 4 11% 22% 27% 19%	1133
August	1st to 10th	Day	17% 1 8% 22% 35% 17%	865
	11th to 20th	Day	20% 3 11% 21% 27% 17%	825
	21st to end	Day	20% 3 13% 25% 22% 16%	748
September	1st to 10th	Day	19% 3 10% 21% 32% 15%	509
	11th to 20th	Day	21% 3 10% 22% 26% 19%	490
	21st to end	Day	24% 3 11% 22% 29% 12%	490
October	1st to 10th	Day	22% 6% 17% 25% 22% 7%	362
	11th to 20th	Day	22% 6% 19% 20% 22% 13%	200
	21st to end	Day	12% 4 11% 33% 28% 13%	220
November	1st to 10th	Day	2 2 9% 34% 38% 16%	200
	11th to 20th	Day	4 4 10% 33% 31% 16%	67
January	1st to 10th	Night	3 1 7% 23% 39% 27%	1220
	11th to 20th	Night	2 1 7% 29% 39% 22%	1184
	21st to end	Night	2 9% 26% 40% 23%	1177
February	1st to 10th	Night	3 8% 23% 38% 28%	1040
	11th to 20th	Night	2 4 21% 40% 33%	932
	21st to end	Night	1 1 8% 22% 41% 26%	785
March	1st to 10th	Night	3 2 10% 27% 34% 24%	760
	11th to 20th	Night	3 9% 29% 40% 19%	760
	21st to end	Night	2 1 11% 22% 41% 21%	738
April	1st to 10th	Night	7% 2 7% 28% 39% 17%	551
	11th to 20th	Night	8% 6% 26% 39% 21%	376
	21st to end	Night	10% 2 10% 24% 32% 21%	380
May	1st to 10th	Night	14% 2 10% 26% 31% 16%	306
	11th to 20th	Night	14% 17% 27% 23% 20%	71
July	21st to end	Night	18% 4 10% 25% 36% 7%	72
	August	1st to 10th	Night	20% 1 10% 26% 31% 12%	239
11th to 20th		Night	21% 3 11% 28% 29% 8%	376
21st to end		Night	29% 2 11% 23% 26% 8%	418
September	1st to 10th	Night	20% 4 13% 21% 34% 9%	532
	11th to 20th	Night	21% 3 12% 24% 27% 13%	679
	21st to end	Night	26% 4 11% 24% 25% 11%	760
October	1st to 10th	Night	23% 4 16% 23% 27% 7%	760
	11th to 20th	Night	23% 6% 17% 25% 21% 8%	796
	21st to end	Night	14% 3 10% 29% 31% 12%	1125
November	1st to 10th	Night	3 1 10% 30% 38% 18%	1075
	11th to 20th	Night	10% 4 16% 27% 29% 14%	1100
	21st to end	Night	9% 3 13% 21% 34% 20%	1228
December	1st to 10th	Night	4 2 11% 32% 29% 22%	1220
	11th to 20th	Night	5% 1 15% 26% 31% 22%	1220
	21st to end	Night	3 1 10% 24% 37% 25%	1342

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