Rankin Inlet
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rankin Inlet clear sky chart from 2005-11-06 to 2026-07-01.

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% 26%	143139
	Night	7% 11% 5% 12% 7% 7% 6% 5% 8% 11% 20%	138009
Transparency	Day	53% 6% 13% 21% 7%	142773
	Night	54% 5% 14% 20% 7%	137961
Seeing	Day	15% 5% 19% 29% 22% 10%	18911
	Night	12% 4 19% 33% 24% 8%	26052

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	1st to 10th	Day	2 8% 4 12% 6% 7% 7% 6% 10% 13% 25%	2362
	11th to 20th	Day	2 8% 5% 16% 9% 7% 9% 7% 12% 9% 17%	2826
	21st to end	Day	1 5% 4 12% 8% 8% 7% 6% 9% 20% 20%	3499
February	1st to 10th	Day	1 4 3 10% 6% 8% 8% 8% 12% 15% 24%	1453
	11th to 20th	Day	1 5% 2 8% 7% 8% 8% 6% 8% 16% 29%	1530
	21st to end	Day	2 5% 4 10% 8% 7% 8% 7% 10% 17% 23%	1552
March	1st to 10th	Day	2 7% 3 12% 9% 11% 10% 7% 11% 12% 16%	4331
	11th to 20th	Day	4 9% 5% 16% 13% 10% 8% 5% 8% 7% 13%	4965
	21st to end	Day	1 4 4 13% 8% 6% 7% 7% 11% 14% 25%	5947
April	1st to 10th	Day	5% 11% 4 10% 5% 7% 9% 7% 10% 9% 23%	2640
	11th to 20th	Day	6% 9% 4 8% 8% 8% 8% 6% 7% 10% 26%	2899
	21st to end	Day	8% 8% 4 11% 8% 9% 7% 5% 7% 7% 25%	3052
May	1st to 10th	Day	11% 19% 7% 16% 10% 6% 5% 3 4 4 16%	9420
	11th to 20th	Day	9% 10% 5% 19% 8% 6% 5% 4 4 6% 24%	9598
	21st to end	Day	9% 9% 5% 11% 8% 7% 6% 5% 6% 8% 26%	11613
June	1st to 10th	Day	14% 13% 4 10% 6% 5% 4 4 6% 7% 28%	3780
	11th to 20th	Day	13% 10% 2 7% 6% 6% 4 4 6% 7% 35%	3916
	21st to end	Day	11% 7% 3 7% 5% 5% 6% 5% 7% 7% 36%	3990
July	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 4 7% 8% 43%	8217
	11th to 20th	Day	8% 7% 3 9% 6% 6% 6% 4 6% 8% 37%	8076
	21st to end	Day	13% 7% 3 7% 5% 4 5% 4 6% 8% 37%	8321
August	1st to 10th	Day	14% 7% 2 7% 4 4 4 3 5% 7% 42%	5186
	11th to 20th	Day	14% 7% 3 7% 5% 5% 4 4 6% 8% 37%	4752
	21st to end	Day	19% 10% 3 9% 5% 4 4 4 5% 6% 32%	5038
September	1st to 10th	Day	19% 12% 3 8% 7% 5% 5% 4 5% 6% 25%	2514
	11th to 20th	Day	21% 17% 6% 11% 5% 4 5% 4 5% 5% 19%	2400
	21st to end	Day	22% 16% 5% 8% 5% 4 4 3 4 5% 24%	2099
October	1st to 10th	Day	20% 24% 12% 12% 5% 4 4 2 3 4 10%	3260
	11th to 20th	Day	20% 29% 9% 14% 5% 3 3 2 3 3 10%	2733
	21st to end	Day	15% 21% 10% 26% 11% 6% 3 2 1 2 3	2768
November	1st to 10th	Day	10% 22% 8% 12% 7% 10% 9% 6% 7% 5% 4	1306
	11th to 20th	Day	10% 15% 4 11% 8% 9% 10% 7% 7% 9% 12%	1239
	21st to end	Day	8% 12% 4 11% 8% 9% 9% 8% 7% 11% 14%	913
December	1st to 10th	Day	1 7% 3 10% 8% 7% 8% 5% 11% 21% 18%	1350
	11th to 20th	Day	3 8% 4 7% 4 7% 7% 8% 16% 20% 15%	1548
	21st to end	Day	6% 17% 9% 18% 10% 7% 6% 3 4 7% 15%	2046
January	1st to 10th	Night	2 8% 4 11% 7% 7% 7% 5% 10% 16% 24%	10561
	11th to 20th	Night	2 9% 6% 16% 8% 7% 8% 6% 9% 11% 18%	10075
	21st to end	Night	2 7% 4 9% 7% 8% 7% 6% 11% 18% 22%	10694
February	1st to 10th	Night	2 4 2 10% 8% 10% 10% 6% 13% 15% 21%	3166
	11th to 20th	Night	2 6% 3 7% 8% 8% 9% 7% 11% 14% 23%	2977
	21st to end	Night	1 5% 3 11% 8% 6% 7% 6% 11% 16% 26%	2254
March	1st to 10th	Night	2 4 2 11% 9% 9% 9% 8% 14% 11% 20%	5752
	11th to 20th	Night	3 13% 6% 15% 11% 10% 8% 7% 7% 6% 15%	5245
	21st to end	Night	1 4 3 11% 10% 8% 9% 6% 11% 13% 24%	5226
April	1st to 10th	Night	5% 10% 3 10% 6% 7% 7% 5% 8% 11% 27%	1979
	11th to 20th	Night	5% 8% 3 9% 7% 7% 8% 5% 8% 8% 32%	1672
	21st to end	Night	7% 9% 3 14% 8% 8% 5% 5% 6% 8% 28%	1567
May	1st to 10th	Night	12% 20% 6% 16% 12% 5% 3 2 3 3 16%	3528
	11th to 20th	Night	8% 10% 7% 21% 9% 6% 5% 3 5% 6% 21%	3280
	21st to end	Night	10% 9% 5% 12% 6% 5% 7% 5% 7% 9% 25%	2591
June	1st to 10th	Night	16% 9% 5% 10% 7% 4 4 3 6% 8% 29%	840
	11th to 20th	Night	13% 10% 3 8% 6% 4 4 5% 7% 7% 35%	701
	21st to end	Night	13% 12% 2 5% 4 5% 4 4 7% 8% 35%	630
July	1st to 10th	Night	13% 8% 3 9% 5% 5% 5% 5% 6% 7% 34%	1763
	11th to 20th	Night	8% 9% 3 9% 7% 6% 6% 5% 7% 7% 34%	1898
	21st to end	Night	13% 8% 3 7% 4 4 5% 4 6% 9% 37%	2525
August	1st to 10th	Night	14% 7% 2 6% 4 4 5% 6% 6% 9% 37%	1973
	11th to 20th	Night	14% 7% 3 8% 4 4 4 3 5% 6% 42%	2307
	21st to end	Night	18% 8% 3 7% 5% 4 5% 3 5% 8% 34%	2871
September	1st to 10th	Night	20% 13% 4 8% 5% 4 6% 3 5% 7% 25%	1884
	11th to 20th	Night	19% 14% 4 9% 6% 5% 5% 3 6% 5% 23%	2000
	21st to end	Night	21% 17% 8% 9% 4 4 4 3 4 6% 20%	2280
October	1st to 10th	Night	23% 25% 12% 11% 4 4 3 3 4 3 9%	3920
	11th to 20th	Night	21% 25% 10% 15% 5% 3 3 2 3 3 11%	4409
	21st to end	Night	14% 24% 11% 26% 10% 5% 3 2 2 2 2	5032
November	1st to 10th	Night	12% 21% 6% 15% 9% 9% 8% 6% 6% 4 3	3208
	11th to 20th	Night	9% 17% 6% 11% 7% 8% 10% 7% 7% 9% 9%	3381
	21st to end	Night	8% 14% 4 12% 8% 8% 8% 6% 8% 11% 13%	3707
December	1st to 10th	Night	2 6% 3 13% 9% 7% 8% 6% 10% 20% 16%	6060
	11th to 20th	Night	3 9% 4 10% 7% 8% 7% 6% 15% 19% 14%	6879
	21st to end	Night	6% 17% 8% 17% 8% 6% 6% 5% 7% 8% 12%	9174

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	42% 5% 18% 23% 12%	2362
	11th to 20th	Day	55% 6% 15% 19% 5%	2841
	21st to end	Day	44% 6% 17% 20% 13% 1	3499
February	1st to 10th	Day	40% 8% 18% 29% 6%	1453
	11th to 20th	Day	38% 5% 20% 25% 11%	1537
	21st to end	Day	41% 4 13% 27% 14%	1552
March	1st to 10th	Day	55% 5% 11% 17% 12%	4331
	11th to 20th	Day	65% 5% 7% 16% 7%	4967
	21st to end	Day	42% 5% 7% 26% 19% 1	5947
April	1st to 10th	Day	50% 6% 11% 20% 12%	2640
	11th to 20th	Day	52% 5% 10% 22% 11%	2899
	21st to end	Day	56% 6% 9% 20% 9%	3052
May	1st to 10th	Day	71% 5% 6% 11% 6%	9417
	11th to 20th	Day	60% 6% 8% 19% 7%	9602
	21st to end	Day	53% 7% 14% 22% 4	11618
June	1st to 10th	Day	56% 6% 12% 21% 5%	3780
	11th to 20th	Day	49% 6% 12% 28% 6%	3916
	21st to end	Day	43% 8% 16% 29% 4	3990
July	1st to 10th	Day	36% 6% 13% 37% 6% 1	8128
	11th to 20th	Day	43% 7% 15% 27% 8%	7977
	21st to end	Day	43% 6% 17% 29% 6%	8087
August	1st to 10th	Day	42% 5% 19% 25% 7% 1	5168
	11th to 20th	Day	43% 6% 20% 22% 7% 2	4797
	21st to end	Day	53% 7% 18% 20% 2	5037
September	1st to 10th	Day	60% 6% 17% 15% 2	2514
	11th to 20th	Day	67% 7% 15% 9% 2	2400
	21st to end	Day	64% 6% 13% 15% 2	2099
October	1st to 10th	Day	77% 5% 9% 9%	3260
	11th to 20th	Day	79% 5% 8% 7% 2	2733
	21st to end	Day	84% 7% 4 4 1	2768
November	1st to 10th	Day	68% 5% 17% 9% 1	1306
	11th to 20th	Day	56% 8% 16% 17% 2	1239
	21st to end	Day	55% 9% 17% 16% 2	913
December	1st to 10th	Day	43% 6% 25% 24% 3	1350
	11th to 20th	Day	38% 8% 21% 30% 3	1548
	21st to end	Day	70% 4 8% 8% 8% 2	2046
January	1st to 10th	Night	43% 5% 15% 27% 10%	10562
	11th to 20th	Night	54% 6% 16% 20% 4	10122
	21st to end	Night	41% 5% 17% 22% 14% 1	10695
February	1st to 10th	Night	44% 6% 18% 26% 5%	3166
	11th to 20th	Night	42% 6% 19% 23% 9%	2980
	21st to end	Night	41% 5% 12% 28% 13%	2254
March	1st to 10th	Night	47% 5% 11% 22% 14%	5752
	11th to 20th	Night	65% 5% 7% 16% 8%	5245
	21st to end	Night	44% 5% 9% 25% 15% 2	5226
April	1st to 10th	Night	46% 6% 12% 24% 12% 1	1979
	11th to 20th	Night	45% 4 12% 26% 12% 1	1672
	21st to end	Night	52% 4 10% 24% 9%	1567
May	1st to 10th	Night	72% 4 5% 11% 7%	3528
	11th to 20th	Night	59% 5% 9% 18% 8%	3280
	21st to end	Night	51% 7% 13% 24% 4	2591
June	1st to 10th	Night	50% 5% 16% 22% 7%	840
	11th to 20th	Night	46% 6% 13% 26% 9%	701
	21st to end	Night	44% 5% 15% 32% 4	630
July	1st to 10th	Night	46% 6% 13% 28% 8%	1743
	11th to 20th	Night	45% 7% 14% 23% 12%	1874
	21st to end	Night	40% 7% 16% 33% 4	2454
August	1st to 10th	Night	41% 6% 16% 29% 8%	1967
	11th to 20th	Night	43% 5% 17% 24% 7% 3	2328
	21st to end	Night	50% 7% 18% 22% 3	2871
September	1st to 10th	Night	58% 7% 20% 14% 2	1884
	11th to 20th	Night	60% 7% 19% 12% 1	2000
	21st to end	Night	65% 6% 13% 14% 2	2280
October	1st to 10th	Night	78% 5% 9% 8%	3920
	11th to 20th	Night	79% 4 8% 8% 2	4409
	21st to end	Night	84% 5% 7% 4	5032
November	1st to 10th	Night	70% 5% 13% 11% 1	3208
	11th to 20th	Night	59% 7% 16% 17% 2	3381
	21st to end	Night	58% 6% 16% 17% 3	3707
December	1st to 10th	Night	45% 7% 24% 22% 3	6060
	11th to 20th	Night	45% 5% 16% 32% 3	6879
	21st to end	Night	65% 4 12% 10% 8%	9174

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	4 4 12% 34% 33% 15%	110
	11th to 20th	Day	5% 7% 30% 31% 22% 5%	110
	21st to end	Day	2 4 21% 42% 23% 9%	173
February	1st to 10th	Day	1 3 15% 34% 27% 20%	322
	11th to 20th	Day	2 2 14% 42% 30% 11%	330
	21st to end	Day	2 3 16% 28% 34% 18%	273
March	1st to 10th	Day	3 3 15% 34% 28% 18%	330
	11th to 20th	Day	7% 6% 15% 29% 31% 12%	330
	21st to end	Day	5% 5% 21% 28% 23% 19%	518
April	1st to 10th	Day	8% 6% 20% 29% 23% 14%	660
	11th to 20th	Day	7% 3 20% 30% 27% 12%	740
	21st to end	Day	8% 5% 18% 29% 26% 13%	750
May	1st to 10th	Day	12% 8% 17% 26% 27% 9%	753
	11th to 20th	Day	14% 8% 22% 30% 20% 6%	778
	21st to end	Day	17% 6% 19% 29% 22% 8%	1072
June	1st to 10th	Day	19% 5% 20% 28% 20% 8%	990
	11th to 20th	Day	17% 6% 22% 32% 17% 6%	1126
	21st to end	Day	14% 4 22% 29% 23% 7%	1200
July	1st to 10th	Day	16% 4 19% 29% 23% 9%	947
	11th to 20th	Day	13% 5% 20% 33% 20% 8%	880
	21st to end	Day	16% 4 16% 30% 23% 10%	794
August	1st to 10th	Day	19% 5% 17% 28% 21% 10%	726
	11th to 20th	Day	21% 3 15% 28% 22% 10%	715
	21st to end	Day	19% 6% 21% 28% 18% 7%	803
September	1st to 10th	Day	26% 8% 16% 24% 19% 7%	641
	11th to 20th	Day	26% 8% 18% 26% 18% 5%	530
	21st to end	Day	32% 7% 21% 19% 16% 5%	380
October	1st to 10th	Day	19% 15% 23% 24% 14% 5%	330
	11th to 20th	Day	31% 7% 20% 19% 17% 6%	330
	21st to end	Day	23% 7% 18% 29% 17% 6%	341
November	1st to 10th	Day	13% 6% 19% 33% 19% 10%	220
	11th to 20th	Day	10% 10% 21% 37% 12% 10%	220
	21st to end	Day	16% 5% 15% 27% 26% 11%	148
December	1st to 10th	Day	7% 4 14% 35% 31% 9%	110
	11th to 20th	Day	5% 4 20% 34% 25% 14%	110
	21st to end	Day	8% 2 21% 29% 26% 13%	121
January	1st to 10th	Night	5% 3 20% 34% 28% 11%	1160
	11th to 20th	Night	6% 4 23% 36% 21% 9%	1069
	21st to end	Night	3 4 24% 37% 23% 9%	1155
February	1st to 10th	Night	3 4 17% 36% 27% 14%	1050
	11th to 20th	Night	4 2 15% 40% 26% 14%	1029
	21st to end	Night	3 2 17% 37% 32% 10%	865
March	1st to 10th	Night	6% 3 20% 32% 29% 9%	961
	11th to 20th	Night	5% 3 15% 37% 31% 9%	707
	21st to end	Night	5% 6% 19% 32% 29% 10%	693
April	1st to 10th	Night	10% 4 19% 29% 29% 9%	630
	11th to 20th	Night	7% 4 17% 35% 30% 6%	623
	21st to end	Night	10% 3 19% 32% 29% 8%	611
May	1st to 10th	Night	13% 7% 19% 30% 27% 5%	420
	11th to 20th	Night	13% 4 25% 35% 20% 2	342
	21st to end	Night	17% 4 17% 30% 26% 5%	227
June	1st to 10th	Night	17% 6% 20% 33% 20% 4	210
	11th to 20th	Night	12% 4 20% 39% 24% 1	210
	21st to end	Night	14% 7% 16% 33% 28% 2	210
July	1st to 10th	Night	16% 4 17% 33% 28% 2	195
	11th to 20th	Night	13% 3 20% 39% 22% 4	194
	21st to end	Night	19% 3 10% 38% 28% 2	244
August	1st to 10th	Night	17% 4 18% 30% 28% 2	408
	11th to 20th	Night	23% 4 10% 31% 27% 5%	594
	21st to end	Night	20% 5% 17% 34% 21% 3	660
September	1st to 10th	Night	25% 7% 13% 30% 23% 3	600
	11th to 20th	Night	24% 4 19% 34% 17% 2	600
	21st to end	Night	28% 7% 21% 26% 17% 2	731
October	1st to 10th	Night	26% 8% 23% 26% 14% 3	800
	11th to 20th	Night	28% 5% 18% 27% 19% 5%	912
	21st to end	Night	26% 4 23% 28% 15% 3	1100
November	1st to 10th	Night	18% 5% 21% 32% 18% 6%	1025
	11th to 20th	Night	14% 6% 23% 32% 18% 7%	1061
	21st to end	Night	12% 5% 17% 31% 24% 10%	1160
December	1st to 10th	Night	6% 3 18% 38% 24% 11%	1160
	11th to 20th	Night	7% 5% 22% 30% 23% 13%	1160
	21st to end	Night	10% 5% 20% 28% 23% 13%	1276

Page generated at 2026-06-28 01:10:48. Version ac07

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