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 2025-02-25.

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% 11% 4 11% 7% 6% 6% 4 6% 8% 27%	111106
	Night	8% 12% 5% 12% 7% 6% 6% 5% 8% 10% 21%	116276
Transparency	Day	52% 6% 14% 21% 7%	110790
	Night	54% 5% 14% 19% 7%	116241
Seeing	Day	15% 5% 19% 29% 22% 10%	16940
	Night	13% 4 19% 33% 24% 8%	24469

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 9% 3 8% 4 6% 6% 6% 10% 13% 31%	1820
	11th to 20th	Day	2 9% 5% 16% 10% 8% 8% 6% 9% 7% 20%	2172
	21st to end	Day	1 5% 3 10% 7% 7% 6% 6% 9% 22% 23%	2697
February	1st to 10th	Day	1 4 3 10% 6% 8% 8% 8% 12% 14% 25%	1384
	11th to 20th	Day	1 5% 2 8% 7% 8% 8% 6% 9% 16% 30%	1455
	21st to end	Day	2 6% 4 9% 8% 7% 8% 7% 10% 16% 23%	1444
March	1st to 10th	Day	3 11% 4 11% 7% 8% 8% 5% 9% 12% 20%	2955
	11th to 20th	Day	5% 10% 6% 17% 11% 8% 5% 5% 10% 9% 14%	3400
	21st to end	Day	2 5% 4 14% 9% 7% 7% 6% 8% 10% 28%	4057
April	1st to 10th	Day	6% 11% 4 10% 5% 7% 9% 6% 10% 8% 23%	2388
	11th to 20th	Day	6% 9% 3 8% 9% 8% 8% 6% 7% 9% 26%	2620
	21st to end	Day	8% 7% 3 11% 8% 9% 7% 6% 7% 8% 26%	2761
May	1st to 10th	Day	12% 19% 7% 15% 9% 6% 5% 3 4 4 17%	5070
	11th to 20th	Day	11% 10% 5% 13% 7% 5% 5% 4 5% 7% 28%	5148
	21st to end	Day	11% 12% 6% 12% 9% 6% 5% 4 5% 7% 23%	6205
June	1st to 10th	Day	14% 13% 4 10% 5% 5% 4 4 5% 7% 29%	3420
	11th to 20th	Day	11% 9% 2 7% 6% 6% 5% 4 6% 7% 36%	3543
	21st to end	Day	12% 8% 3 7% 6% 5% 6% 5% 7% 7% 35%	3610
July	1st to 10th	Day	11% 5% 2 5% 5% 4 5% 5% 7% 8% 44%	5742
	11th to 20th	Day	9% 7% 3 8% 5% 5% 5% 4 6% 8% 38%	5644
	21st to end	Day	9% 6% 3 6% 5% 4 5% 4 7% 9% 41%	5788
August	1st to 10th	Day	14% 7% 2 7% 4 4 4 3 5% 7% 41%	5027
	11th to 20th	Day	13% 7% 3 7% 5% 5% 4 4 6% 8% 37%	4604
	21st to end	Day	20% 10% 3 9% 5% 4 4 3 5% 6% 32%	4884
September	1st to 10th	Day	20% 12% 3 8% 7% 5% 4 4 5% 6% 25%	2389
	11th to 20th	Day	21% 16% 5% 10% 5% 4 5% 4 5% 5% 19%	2280
	21st to end	Day	23% 16% 5% 8% 4 4 4 3 5% 5% 24%	1995
October	1st to 10th	Day	20% 24% 12% 12% 4 4 4 2 3 4 10%	3160
	11th to 20th	Day	19% 29% 9% 14% 5% 3 3 2 3 3 10%	2649
	21st to end	Day	16% 21% 10% 26% 11% 6% 3 2 1 1 2	2682
November	1st to 10th	Day	10% 21% 8% 12% 7% 11% 9% 6% 7% 5% 4	1243
	11th to 20th	Day	9% 13% 4 11% 8% 9% 10% 8% 7% 9% 13%	1180
	21st to end	Day	8% 12% 4 11% 7% 9% 8% 8% 7% 11% 14%	870
December	1st to 10th	Day	2 7% 3 10% 8% 7% 8% 5% 10% 21% 19%	1310
	11th to 20th	Day	3 8% 4 7% 4 8% 7% 8% 17% 19% 15%	1508
	21st to end	Day	6% 17% 9% 18% 10% 7% 6% 3 3 6% 15%	2002
January	1st to 10th	Night	2 8% 3 9% 6% 7% 6% 5% 10% 16% 29%	8145
	11th to 20th	Night	3 11% 7% 16% 8% 7% 8% 5% 8% 8% 20%	7727
	21st to end	Night	3 6% 3 7% 6% 7% 6% 6% 11% 20% 26%	8267
February	1st to 10th	Night	2 4 2 9% 8% 9% 10% 7% 13% 15% 21%	3015
	11th to 20th	Night	2 5% 3 7% 8% 8% 10% 7% 12% 15% 23%	2832
	21st to end	Night	1 6% 4 12% 8% 5% 7% 6% 10% 15% 26%	2105
March	1st to 10th	Night	3 6% 3 11% 9% 9% 7% 6% 9% 11% 25%	3902
	11th to 20th	Night	5% 15% 6% 14% 9% 7% 6% 6% 7% 7% 18%	3589
	21st to end	Night	2 5% 3 14% 12% 8% 8% 5% 7% 9% 26%	3574
April	1st to 10th	Night	6% 10% 3 11% 6% 7% 7% 5% 7% 11% 27%	1791
	11th to 20th	Night	6% 8% 3 9% 8% 8% 8% 5% 8% 8% 30%	1511
	21st to end	Night	8% 8% 3 13% 8% 9% 5% 5% 6% 8% 28%	1418
May	1st to 10th	Night	15% 18% 5% 14% 8% 5% 3 2 4 4 21%	1900
	11th to 20th	Night	9% 11% 5% 13% 6% 4 5% 3 5% 7% 31%	1750
	21st to end	Night	10% 12% 6% 12% 6% 5% 6% 4 5% 7% 29%	1381
June	1st to 10th	Night	15% 10% 5% 9% 6% 4 4 3 5% 8% 32%	760
	11th to 20th	Night	11% 9% 3 8% 6% 4 5% 5% 7% 7% 36%	635
	21st to end	Night	15% 12% 2 4 5% 5% 5% 4 8% 8% 33%	570
July	1st to 10th	Night	14% 8% 3 9% 5% 6% 4 4 6% 7% 35%	1227
	11th to 20th	Night	8% 9% 3 8% 7% 7% 6% 6% 7% 6% 34%	1322
	21st to end	Night	11% 8% 3 6% 3 4 5% 5% 7% 9% 40%	1766
August	1st to 10th	Night	15% 7% 2 6% 4 4 4 6% 6% 9% 36%	1912
	11th to 20th	Night	14% 7% 3 8% 4 4 4 3 5% 6% 42%	2235
	21st to end	Night	18% 7% 3 7% 5% 4 5% 3 5% 7% 34%	2783
September	1st to 10th	Night	21% 13% 4 8% 5% 4 6% 4 5% 6% 24%	1789
	11th to 20th	Night	19% 14% 4 8% 6% 5% 5% 3 6% 5% 24%	1900
	21st to end	Night	22% 18% 8% 8% 4 4 4 3 4 6% 19%	2165
October	1st to 10th	Night	23% 25% 12% 11% 4 4 3 3 4 3 10%	3800
	11th to 20th	Night	21% 25% 10% 15% 5% 3 3 2 3 3 11%	4273
	21st to end	Night	15% 24% 11% 26% 10% 5% 3 2 2 2 1	4876
November	1st to 10th	Night	12% 21% 6% 16% 9% 10% 8% 6% 6% 4 3	3051
	11th to 20th	Night	8% 16% 6% 11% 7% 8% 10% 7% 7% 9% 10%	3220
	21st to end	Night	8% 14% 4 12% 8% 8% 8% 6% 7% 11% 14%	3530
December	1st to 10th	Night	2 6% 3 13% 9% 7% 8% 5% 10% 20% 17%	5880
	11th to 20th	Night	3 9% 4 10% 7% 8% 7% 6% 14% 19% 14%	6699
	21st to end	Night	6% 17% 8% 17% 8% 6% 5% 5% 7% 8% 12%	8976

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	38% 5% 22% 21% 15%	1820
	11th to 20th	Day	57% 6% 17% 14% 6%	2187
	21st to end	Day	38% 6% 14% 25% 16% 1	2697
February	1st to 10th	Day	39% 8% 18% 29% 6%	1384
	11th to 20th	Day	38% 5% 21% 26% 11%	1462
	21st to end	Day	41% 4 14% 26% 14%	1444
March	1st to 10th	Day	51% 5% 15% 20% 9%	2955
	11th to 20th	Day	61% 5% 9% 18% 7%	3402
	21st to end	Day	47% 5% 8% 19% 18% 1	4057
April	1st to 10th	Day	51% 7% 11% 18% 13%	2388
	11th to 20th	Day	52% 6% 11% 21% 10%	2620
	21st to end	Day	55% 6% 10% 20% 9%	2761
May	1st to 10th	Day	70% 4 7% 12% 6%	5070
	11th to 20th	Day	55% 6% 8% 19% 12%	5152
	21st to end	Day	58% 6% 11% 21% 5%	6206
June	1st to 10th	Day	55% 6% 12% 21% 5%	3420
	11th to 20th	Day	46% 6% 12% 30% 6%	3543
	21st to end	Day	45% 8% 16% 27% 4	3610
July	1st to 10th	Day	35% 7% 13% 39% 6%	5653
	11th to 20th	Day	42% 7% 15% 32% 5%	5545
	21st to end	Day	37% 6% 19% 31% 7%	5605
August	1st to 10th	Day	43% 5% 19% 24% 8% 1	5009
	11th to 20th	Day	43% 6% 20% 22% 7% 2	4649
	21st to end	Day	54% 7% 18% 19% 2	4883
September	1st to 10th	Day	60% 6% 17% 15% 2	2389
	11th to 20th	Day	67% 7% 16% 10% 1	2280
	21st to end	Day	63% 6% 13% 15% 3	1995
October	1st to 10th	Day	77% 5% 9% 9%	3160
	11th to 20th	Day	79% 5% 8% 7% 2	2649
	21st to end	Day	84% 7% 4 4 1	2682
November	1st to 10th	Day	68% 5% 17% 9% 1	1243
	11th to 20th	Day	55% 9% 16% 18% 2	1180
	21st to end	Day	55% 9% 17% 16% 2	870
December	1st to 10th	Day	43% 5% 25% 24% 3	1310
	11th to 20th	Day	38% 8% 21% 30% 2	1508
	21st to end	Day	70% 4 8% 8% 8% 2	2002
January	1st to 10th	Night	39% 5% 16% 27% 12%	8145
	11th to 20th	Night	57% 7% 18% 14% 4	7774
	21st to end	Night	36% 4 15% 26% 18% 1	8267
February	1st to 10th	Night	43% 7% 19% 26% 6%	3015
	11th to 20th	Night	41% 7% 20% 24% 9%	2835
	21st to end	Night	42% 5% 12% 27% 14% 1	2105
March	1st to 10th	Night	48% 5% 13% 24% 10%	3902
	11th to 20th	Night	60% 5% 8% 19% 8%	3589
	21st to end	Night	50% 5% 11% 15% 17% 3	3574
April	1st to 10th	Night	47% 7% 13% 21% 12% 1	1791
	11th to 20th	Night	46% 4 13% 24% 12% 1	1511
	21st to end	Night	52% 4 10% 24% 10%	1418
May	1st to 10th	Night	66% 4 7% 14% 8%	1900
	11th to 20th	Night	50% 4 10% 23% 13%	1750
	21st to end	Night	52% 7% 10% 27% 4	1381
June	1st to 10th	Night	49% 5% 16% 24% 7%	760
	11th to 20th	Night	44% 5% 13% 27% 10%	635
	21st to end	Night	46% 5% 15% 30% 4	570
July	1st to 10th	Night	46% 6% 13% 28% 8%	1207
	11th to 20th	Night	44% 7% 12% 27% 9%	1298
	21st to end	Night	36% 7% 17% 35% 5%	1710
August	1st to 10th	Night	42% 6% 16% 28% 8%	1906
	11th to 20th	Night	43% 5% 18% 24% 8% 3	2256
	21st to end	Night	50% 7% 18% 22% 3	2783
September	1st to 10th	Night	58% 7% 19% 13% 2	1789
	11th to 20th	Night	59% 7% 20% 13% 1	1900
	21st to end	Night	66% 6% 12% 14% 2	2165
October	1st to 10th	Night	78% 5% 9% 8%	3800
	11th to 20th	Night	79% 4 8% 8% 2	4273
	21st to end	Night	85% 5% 7% 3	4876
November	1st to 10th	Night	70% 5% 14% 10% 1	3051
	11th to 20th	Night	58% 7% 16% 17% 2	3220
	21st to end	Night	58% 6% 16% 16% 3	3530
December	1st to 10th	Night	45% 7% 24% 21% 3	5880
	11th to 20th	Night	45% 5% 16% 31% 2	6699
	21st to end	Night	66% 4 12% 9% 8%	8976

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 3 11% 32% 35% 15%	100
	11th to 20th	Day	6% 7% 28% 32% 22% 5%	100
	21st to end	Day	1 4 22% 41% 22% 10%	157
February	1st to 10th	Day	1 2 14% 32% 28% 22%	293
	11th to 20th	Day	1 2 13% 41% 31% 12%	300
	21st to end	Day	3 1 16% 25% 38% 18%	237
March	1st to 10th	Day	3 4 17% 33% 27% 17%	270
	11th to 20th	Day	8% 6% 14% 30% 29% 14%	270
	21st to end	Day	5% 6% 24% 27% 21% 17%	437
April	1st to 10th	Day	9% 6% 19% 28% 24% 14%	568
	11th to 20th	Day	7% 3 20% 29% 27% 13%	640
	21st to end	Day	8% 5% 17% 30% 26% 14%	650
May	1st to 10th	Day	12% 6% 16% 26% 29% 11%	653
	11th to 20th	Day	14% 8% 21% 30% 21% 6%	678
	21st to end	Day	17% 6% 20% 26% 22% 9%	940
June	1st to 10th	Day	19% 3 20% 28% 21% 9%	870
	11th to 20th	Day	14% 5% 22% 34% 19% 7%	993
	21st to end	Day	15% 5% 25% 29% 21% 6%	1060
July	1st to 10th	Day	16% 4 18% 29% 24% 9%	885
	11th to 20th	Day	14% 5% 19% 33% 20% 8%	822
	21st to end	Day	16% 4 16% 31% 23% 10%	739
August	1st to 10th	Day	20% 5% 16% 27% 21% 11%	676
	11th to 20th	Day	20% 3 15% 29% 22% 11%	665
	21st to end	Day	20% 6% 21% 28% 18% 7%	748
September	1st to 10th	Day	27% 7% 15% 24% 19% 8%	596
	11th to 20th	Day	27% 7% 18% 25% 18% 5%	490
	21st to end	Day	32% 6% 21% 18% 17% 5%	348
October	1st to 10th	Day	19% 13% 22% 25% 15% 6%	300
	11th to 20th	Day	30% 7% 20% 19% 19% 6%	300
	21st to end	Day	25% 6% 16% 29% 17% 6%	310
November	1st to 10th	Day	12% 5% 19% 35% 20% 11%	200
	11th to 20th	Day	9% 9% 22% 38% 13% 11%	200
	21st to end	Day	16% 6% 16% 26% 25% 10%	135
December	1st to 10th	Day	8% 4 14% 34% 31% 9%	100
	11th to 20th	Day	5% 4 20% 32% 25% 14%	100
	21st to end	Day	8% 3 20% 29% 25% 15%	110
January	1st to 10th	Night	5% 2 20% 34% 28% 11%	1100
	11th to 20th	Night	6% 4 22% 36% 22% 10%	1017
	21st to end	Night	3 4 23% 36% 24% 10%	1100
February	1st to 10th	Night	3 4 17% 35% 27% 15%	1000
	11th to 20th	Night	4 2 14% 40% 26% 15%	979
	21st to end	Night	3 1 16% 37% 33% 10%	808
March	1st to 10th	Night	7% 4 21% 32% 27% 9%	869
	11th to 20th	Night	6% 3 15% 37% 29% 10%	640
	21st to end	Night	6% 7% 20% 32% 26% 10%	627
April	1st to 10th	Night	11% 4 19% 28% 29% 9%	570
	11th to 20th	Night	8% 4 18% 33% 30% 7%	563
	21st to end	Night	10% 3 18% 31% 29% 8%	553
May	1st to 10th	Night	13% 6% 19% 29% 28% 6%	380
	11th to 20th	Night	14% 5% 24% 36% 20% 2	309
	21st to end	Night	19% 4 18% 29% 24% 6%	205
June	1st to 10th	Night	15% 5% 20% 35% 21% 5%	190
	11th to 20th	Night	10% 4 21% 39% 26% 1	190
	21st to end	Night	15% 7% 17% 35% 24% 2	190
July	1st to 10th	Night	17% 4 14% 35% 28% 2	185
	11th to 20th	Night	14% 2 20% 40% 21% 4	184
	21st to end	Night	19% 3 10% 37% 28% 2	232
August	1st to 10th	Night	18% 4 17% 30% 29% 2	387
	11th to 20th	Night	23% 3 11% 31% 27% 5%	564
	21st to end	Night	21% 5% 16% 34% 21% 3	627
September	1st to 10th	Night	26% 7% 12% 30% 22% 3	570
	11th to 20th	Night	24% 4 19% 33% 18% 2	570
	21st to end	Night	29% 7% 21% 25% 17% 2	694
October	1st to 10th	Night	25% 7% 23% 27% 15% 3	760
	11th to 20th	Night	27% 4 17% 27% 20% 5%	866
	21st to end	Night	27% 4 22% 28% 15% 3	1045
November	1st to 10th	Night	17% 5% 20% 33% 18% 6%	975
	11th to 20th	Night	12% 5% 23% 33% 18% 8%	1010
	21st to end	Night	12% 5% 18% 30% 25% 11%	1100
December	1st to 10th	Night	7% 3 18% 37% 24% 11%	1100
	11th to 20th	Night	7% 5% 21% 30% 23% 14%	1100
	21st to end	Night	11% 5% 20% 28% 23% 14%	1210

Page generated at 2025-02-22 05:51:36. Version ac07

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