Inukshuk Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Inukshuk Observatory clear sky chart from 2005-11-06 to 2025-01-07.

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	13% 11% 4 10% 5% 5% 5% 4 5% 7% 32%	105239
	Night	13% 12% 5% 10% 6% 5% 4 3 5% 6% 31%	103919
Transparency	Day	51% 5% 12% 21% 10% 1	108724
	Night	53% 5% 12% 20% 9% 1	108574
Seeing	Day	20% 16% 32% 20% 9% 3	16252
	Night	19% 12% 32% 26% 9% 1	26229

By Month

Percentage Cloud Cover SE (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	11% 16% 8% 20% 7% 5% 4 3 5% 5% 16%	2575
	11th to 20th	Day	7% 18% 6% 16% 10% 8% 9% 4 4 6% 11%	2530
	21st to end	Day	11% 17% 10% 19% 6% 4 4 3 4 6% 15%	2783
February	1st to 10th	Day	8% 13% 5% 12% 5% 6% 6% 5% 6% 7% 26%	1686
	11th to 20th	Day	8% 12% 5% 13% 7% 6% 6% 4 6% 7% 26%	1730
	21st to end	Day	12% 13% 6% 11% 8% 6% 5% 4 5% 6% 24%	1570
March	1st to 10th	Day	11% 11% 3 10% 5% 4 3 3 5% 6% 39%	3120
	11th to 20th	Day	8% 12% 4 13% 8% 5% 6% 4 5% 6% 28%	3338
	21st to end	Day	19% 13% 5% 14% 5% 5% 4 3 4 4 25%	4128
April	1st to 10th	Day	16% 14% 4 9% 5% 5% 5% 4 5% 7% 27%	2280
	11th to 20th	Day	19% 12% 5% 10% 5% 5% 3 3 4 5% 30%	2254
	21st to end	Day	18% 12% 3 8% 4 5% 5% 4 5% 6% 31%	2416
May	1st to 10th	Day	17% 10% 3 7% 5% 4 4 4 5% 6% 37%	4389
	11th to 20th	Day	14% 9% 2 7% 5% 4 4 4 5% 6% 39%	4399
	21st to end	Day	14% 9% 3 8% 5% 5% 5% 3 5% 7% 35%	4824
June	1st to 10th	Day	14% 8% 2 7% 4 4 4 4 6% 8% 40%	2660
	11th to 20th	Day	14% 7% 3 7% 5% 5% 6% 3 7% 7% 36%	2660
	21st to end	Day	13% 7% 3 6% 5% 4 6% 4 7% 10% 36%	2660
July	1st to 10th	Day	14% 4 2 6% 5% 5% 5% 5% 7% 10% 37%	4440
	11th to 20th	Day	7% 4 1 5% 4 5% 4 4 7% 10% 49%	4440
	21st to end	Day	8% 6% 2 6% 5% 5% 5% 5% 7% 8% 45%	4813
August	1st to 10th	Day	12% 6% 3 8% 5% 5% 6% 5% 6% 7% 38%	4423
	11th to 20th	Day	14% 5% 2 5% 4 3 4 3 5% 7% 47%	4032
	21st to end	Day	14% 8% 3 7% 5% 4 4 3 5% 7% 39%	4180
September	1st to 10th	Day	15% 7% 2 6% 4 3 4 3 6% 7% 43%	2280
	11th to 20th	Day	14% 6% 3 6% 5% 5% 4 5% 5% 7% 39%	2223
	21st to end	Day	16% 10% 3 7% 4 4 5% 3 6% 7% 35%	2090
October	1st to 10th	Day	17% 10% 2 7% 4 4 5% 4 5% 8% 34%	1924
	11th to 20th	Day	20% 14% 4 9% 5% 5% 5% 3 4 6% 23%	1876
	21st to end	Day	22% 15% 4 8% 5% 4 3 3 5% 6% 25%	1881
November	1st to 10th	Day	16% 15% 4 7% 5% 4 5% 3 6% 5% 30%	1762
	11th to 20th	Day	15% 18% 5% 14% 6% 5% 4 4 4 4 21%	1673
	21st to end	Day	15% 14% 7% 14% 8% 5% 6% 4 5% 5% 18%	1600
December	1st to 10th	Day	8% 15% 8% 28% 9% 6% 4 3 3 4 12%	2610
	11th to 20th	Day	9% 21% 7% 18% 9% 5% 4 3 4 4 17%	3008
	21st to end	Day	19% 23% 6% 12% 6% 4 3 3 3 5% 16%	3982
January	1st to 10th	Night	12% 16% 6% 19% 7% 6% 4 3 4 5% 19%	4513
	11th to 20th	Night	8% 16% 6% 16% 9% 9% 7% 4 6% 5% 14%	4440
	21st to end	Night	10% 18% 10% 17% 7% 5% 4 3 4 5% 18%	4884
February	1st to 10th	Night	8% 11% 6% 13% 7% 7% 5% 4 6% 6% 27%	2489
	11th to 20th	Night	9% 11% 4 11% 7% 7% 6% 4 7% 7% 28%	2337
	21st to end	Night	12% 15% 6% 10% 7% 5% 5% 4 5% 5% 26%	1884
March	1st to 10th	Night	9% 8% 3 9% 5% 5% 5% 4 6% 9% 37%	3733
	11th to 20th	Night	9% 10% 4 14% 5% 5% 4 4 5% 6% 34%	3651
	21st to end	Night	17% 13% 5% 11% 5% 4 4 3 5% 6% 26%	3503
April	1st to 10th	Night	19% 12% 5% 10% 4 3 3 3 6% 6% 30%	1900
	11th to 20th	Night	21% 10% 4 7% 4 3 3 3 5% 6% 34%	1875
	21st to end	Night	17% 10% 3 8% 5% 4 5% 4 5% 6% 34%	1762
May	1st to 10th	Night	18% 10% 3 6% 4 4 3 3 5% 7% 37%	2514
	11th to 20th	Night	12% 8% 3 8% 5% 4 4 3 5% 5% 44%	2506
	21st to end	Night	15% 8% 3 7% 6% 4 4 4 5% 6% 37%	2743
June	1st to 10th	Night	11% 8% 3 5% 5% 4 4 4 5% 7% 46%	1520
	11th to 20th	Night	13% 7% 3 7% 5% 5% 4 3 5% 7% 39%	1520
	21st to end	Night	13% 6% 2 4 5% 5% 5% 4 6% 10% 41%	1520
July	1st to 10th	Night	15% 5% 2 5% 4 4 4 3 4 8% 47%	2530
	11th to 20th	Night	7% 4 1 4 3 4 4 4 7% 9% 54%	2530
	21st to end	Night	9% 5% 2 5% 4 4 5% 3 5% 6% 53%	2750
August	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 6% 9% 42%	2517
	11th to 20th	Night	13% 6% 2 5% 3 3 4 2 4 6% 51%	2787
	21st to end	Night	15% 9% 3 7% 3 4 3 3 4 6% 45%	3476
September	1st to 10th	Night	11% 6% 2 5% 4 3 4 3 5% 7% 50%	1900
	11th to 20th	Night	11% 7% 2 5% 4 5% 4 4 5% 7% 47%	1938
	21st to end	Night	15% 9% 3 7% 4 4 5% 3 4 7% 39%	2090
October	1st to 10th	Night	16% 7% 2 6% 5% 3 4 4 5% 6% 42%	2251
	11th to 20th	Night	17% 13% 5% 7% 5% 4 5% 4 6% 6% 30%	2303
	21st to end	Night	19% 14% 3 9% 5% 5% 4 4 6% 7% 24%	2717
November	1st to 10th	Night	16% 13% 5% 7% 4 4 4 3 6% 7% 32%	2536
	11th to 20th	Night	14% 16% 6% 12% 6% 5% 5% 3 4 5% 24%	2725
	21st to end	Night	14% 15% 7% 15% 7% 5% 4 4 5% 6% 20%	2800
December	1st to 10th	Night	11% 14% 7% 19% 11% 6% 4 3 5% 5% 14%	4580
	11th to 20th	Night	10% 19% 9% 16% 8% 5% 5% 3 4 4 18%	5199
	21st to end	Night	22% 19% 5% 12% 6% 5% 4 3 4 5% 15%	6996

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	70% 3 8% 15% 4	2576
	11th to 20th	Day	73% 5% 9% 7% 5%	2530
	21st to end	Day	71% 3 11% 10% 4	2783
February	1st to 10th	Day	56% 5% 10% 18% 10%	1686
	11th to 20th	Day	56% 5% 12% 21% 6%	1739
	21st to end	Day	60% 5% 10% 15% 9% 1	1570
March	1st to 10th	Day	48% 4 13% 18% 16% 1	3120
	11th to 20th	Day	56% 5% 13% 18% 8% 1	3338
	21st to end	Day	64% 3 10% 16% 6% 1	4128
April	1st to 10th	Day	57% 6% 10% 17% 10% 1	2280
	11th to 20th	Day	58% 4 7% 21% 9% 1	2254
	21st to end	Day	54% 5% 10% 18% 12% 1	2416
May	1st to 10th	Day	47% 6% 9% 24% 13% 1	4430
	11th to 20th	Day	44% 6% 12% 27% 11% 1	4403
	21st to end	Day	49% 6% 10% 19% 15% 1	4837
June	1st to 10th	Day	41% 6% 14% 26% 12% 1	2660
	11th to 20th	Day	46% 6% 12% 21% 14% 1	2660
	21st to end	Day	42% 8% 16% 24% 10% 1	2660
July	1st to 10th	Day	40% 7% 14% 27% 10% 1	4371
	11th to 20th	Day	29% 7% 16% 34% 13% 2	4365
	21st to end	Day	34% 7% 12% 29% 16%	4662
August	1st to 10th	Day	43% 6% 15% 23% 12% 1	4408
	11th to 20th	Day	36% 6% 14% 32% 12%	4074
	21st to end	Day	44% 6% 15% 24% 11% 1	4179
September	1st to 10th	Day	41% 5% 13% 29% 12%	2280
	11th to 20th	Day	43% 7% 19% 24% 7%	2223
	21st to end	Day	48% 5% 12% 26% 9%	2090
October	1st to 10th	Day	36% 4 13% 29% 18%	3197
	11th to 20th	Day	55% 4 10% 18% 13%	3092
	21st to end	Day	56% 4 16% 19% 4	3081
November	1st to 10th	Day	55% 5% 12% 20% 8% 1	1762
	11th to 20th	Day	68% 4 10% 12% 6%	1673
	21st to end	Day	68% 6% 13% 10% 3 1	1600
December	1st to 10th	Day	77% 5% 6% 10% 3	2610
	11th to 20th	Day	72% 4 6% 10% 6%	3005
	21st to end	Day	73% 4 4 12% 7%	3982
January	1st to 10th	Night	68% 4 9% 16% 3	4513
	11th to 20th	Night	70% 5% 10% 11% 4	4440
	21st to end	Night	69% 4 9% 15% 3	4884
February	1st to 10th	Night	56% 5% 8% 19% 11% 1	2489
	11th to 20th	Night	54% 6% 12% 20% 7% 1	2338
	21st to end	Night	59% 4 12% 17% 7% 1	1884
March	1st to 10th	Night	42% 4 18% 24% 11% 1	3733
	11th to 20th	Night	51% 4 11% 24% 8% 1	3651
	21st to end	Night	59% 5% 10% 17% 8% 1	3503
April	1st to 10th	Night	55% 5% 9% 16% 14% 1	1900
	11th to 20th	Night	52% 4 9% 20% 12% 2	1875
	21st to end	Night	50% 6% 9% 19% 14% 1	1762
May	1st to 10th	Night	46% 5% 14% 21% 12% 1	2538
	11th to 20th	Night	41% 6% 10% 26% 16% 2	2507
	21st to end	Night	46% 7% 15% 17% 14% 1	2751
June	1st to 10th	Night	37% 8% 15% 28% 13%	1520
	11th to 20th	Night	44% 5% 13% 21% 15% 1	1520
	21st to end	Night	38% 7% 16% 28% 10% 1	1520
July	1st to 10th	Night	37% 4 18% 26% 13% 2	2490
	11th to 20th	Night	25% 7% 16% 37% 14% 1	2482
	21st to end	Night	31% 7% 12% 30% 18% 2	2662
August	1st to 10th	Night	38% 7% 15% 23% 16% 1	2508
	11th to 20th	Night	35% 6% 17% 27% 12% 3	2811
	21st to end	Night	42% 5% 13% 26% 13% 2	3476
September	1st to 10th	Night	34% 6% 14% 32% 13% 1	1900
	11th to 20th	Night	35% 6% 16% 33% 8%	1938
	21st to end	Night	44% 5% 15% 26% 9% 1	2090
October	1st to 10th	Night	33% 4 8% 35% 18% 1	3758
	11th to 20th	Night	44% 4 12% 28% 12%	3826
	21st to end	Night	57% 4 11% 20% 7%	4467
November	1st to 10th	Night	52% 5% 13% 20% 10%	2536
	11th to 20th	Night	62% 5% 12% 13% 7% 1	2725
	21st to end	Night	65% 5% 13% 13% 3 1	2800
December	1st to 10th	Night	71% 5% 11% 10% 2	4580
	11th to 20th	Night	70% 4 7% 12% 7%	5201
	21st to end	Night	72% 4 5% 12% 7%	6996

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	21% 18% 32% 24% 5% 1	288
	11th to 20th	Day	23% 17% 37% 17% 4	270
	21st to end	Day	23% 14% 42% 18% 3	297
February	1st to 10th	Day	18% 25% 39% 13% 3 1	270
	11th to 20th	Day	21% 27% 37% 12% 3	270
	21st to end	Day	24% 22% 46% 7% 1	225
March	1st to 10th	Day	18% 25% 41% 14% 3	270
	11th to 20th	Day	22% 21% 34% 16% 5% 1	270
	21st to end	Day	26% 18% 32% 15% 7% 2	482
April	1st to 10th	Day	28% 17% 32% 19% 4 1	460
	11th to 20th	Day	30% 19% 27% 18% 5% 1	452
	21st to end	Day	27% 17% 28% 20% 6% 2	460
May	1st to 10th	Day	22% 22% 30% 19% 6% 2	643
	11th to 20th	Day	21% 18% 30% 19% 8% 2	675
	21st to end	Day	19% 15% 32% 21% 10% 2	734
June	1st to 10th	Day	16% 18% 32% 23% 8% 4	680
	11th to 20th	Day	17% 15% 35% 23% 7% 3	680
	21st to end	Day	16% 13% 33% 22% 13% 3	680
July	1st to 10th	Day	8% 9% 33% 28% 15% 8%	671
	11th to 20th	Day	12% 12% 31% 25% 15% 5%	668
	21st to end	Day	9% 8% 32% 29% 14% 7%	739
August	1st to 10th	Day	14% 9% 26% 28% 18% 5%	676
	11th to 20th	Day	17% 7% 23% 28% 22% 5%	599
	21st to end	Day	19% 10% 26% 23% 16% 5%	539
September	1st to 10th	Day	19% 13% 23% 25% 14% 5%	490
	11th to 20th	Day	14% 9% 32% 30% 11% 3	490
	21st to end	Day	22% 17% 26% 21% 10% 4	490
October	1st to 10th	Day	22% 17% 31% 19% 9% 2	324
	11th to 20th	Day	27% 24% 32% 13% 4	300
	21st to end	Day	35% 23% 32% 8% 2	330
November	1st to 10th	Day	26% 18% 38% 15% 3 1	300
	11th to 20th	Day	28% 25% 34% 9% 3 1	300
	21st to end	Day	24% 23% 40% 9% 3	300
December	1st to 10th	Day	20% 18% 43% 13% 5%	300
	11th to 20th	Day	26% 27% 33% 11% 2	300
	21st to end	Day	29% 24% 33% 11% 2 1	330
January	1st to 10th	Night	18% 17% 39% 22% 5%	981
	11th to 20th	Night	20% 13% 40% 20% 6% 1	950
	21st to end	Night	19% 11% 40% 24% 6%	1045
February	1st to 10th	Night	14% 17% 38% 24% 7%	950
	11th to 20th	Night	16% 18% 36% 23% 6%	863
	21st to end	Night	20% 15% 40% 23% 2	628
March	1st to 10th	Night	17% 16% 36% 24% 7% 1	760
	11th to 20th	Night	18% 15% 36% 25% 6%	676
	21st to end	Night	20% 12% 30% 27% 10% 1	627
April	1st to 10th	Night	24% 13% 34% 23% 5% 1	570
	11th to 20th	Night	27% 13% 27% 26% 7%	563
	21st to end	Night	23% 11% 29% 28% 8% 1	570
May	1st to 10th	Night	22% 13% 32% 27% 6% 1	570
	11th to 20th	Night	20% 9% 34% 30% 8% 1	561
	21st to end	Night	17% 7% 28% 36% 12%	617
June	1st to 10th	Night	14% 10% 30% 35% 11% 1	570
	11th to 20th	Night	19% 6% 31% 33% 10%	570
	21st to end	Night	16% 5% 24% 39% 14% 2	570
July	1st to 10th	Night	9% 4 23% 39% 24% 1	555
	11th to 20th	Night	12% 7% 27% 31% 22% 1	552
	21st to end	Night	8% 3 25% 39% 21% 3	624
August	1st to 10th	Night	10% 4 22% 44% 19% 2	567
	11th to 20th	Night	15% 3 19% 34% 27% 2	564
	21st to end	Night	16% 6% 24% 33% 19% 2	627
September	1st to 10th	Night	16% 6% 26% 32% 17% 3	570
	11th to 20th	Night	13% 7% 30% 32% 16% 2	608
	21st to end	Night	19% 10% 27% 29% 13% 1	760
October	1st to 10th	Night	21% 11% 29% 26% 12% 1	760
	11th to 20th	Night	23% 16% 30% 24% 6%	760
	21st to end	Night	26% 11% 32% 23% 7%	836
November	1st to 10th	Night	25% 12% 35% 22% 6% 1	780
	11th to 20th	Night	21% 19% 34% 20% 5%	925
	21st to end	Night	23% 19% 34% 21% 4	1000
December	1st to 10th	Night	22% 15% 38% 19% 6%	1000
	11th to 20th	Night	20% 17% 36% 19% 6% 1	1000
	21st to end	Night	28% 16% 33% 19% 4	1100

Page generated at 2025-01-04 02:24:01. Version ac07

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