Caribou
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caribou clear sky chart from 2005-11-06 to 2026-04-02.

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% 11% 4 9% 5% 5% 4 4 5% 7% 29%	132007
	Night	19% 13% 5% 11% 6% 5% 4 3 5% 6% 25%	129991
Transparency	Day	55% 8% 12% 18% 7% 1	135540
	Night	57% 7% 11% 17% 7% 1	134549
Seeing	Day	23% 15% 29% 23% 9% 2	19387
	Night	25% 15% 29% 23% 7% 1	26947

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	14% 20% 8% 19% 7% 5% 3 2 3 4 14%	4690
	11th to 20th	Day	16% 18% 8% 13% 6% 5% 4 3 4 4 18%	4681
	21st to end	Day	10% 11% 5% 12% 7% 7% 7% 4 5% 6% 27%	5627
February	1st to 10th	Day	17% 15% 4 10% 6% 6% 5% 4 5% 5% 24%	1890
	11th to 20th	Day	15% 15% 5% 10% 6% 5% 5% 4 4 5% 26%	1843
	21st to end	Day	10% 13% 5% 8% 6% 5% 5% 4 6% 8% 31%	1635
March	1st to 10th	Day	18% 12% 4 11% 8% 6% 5% 3 4 5% 25%	4827
	11th to 20th	Day	12% 13% 5% 10% 6% 5% 5% 4 5% 7% 26%	5090
	21st to end	Day	20% 17% 6% 13% 6% 4 4 3 4 5% 19%	5717
April	1st to 10th	Day	19% 14% 4 8% 5% 4 3 3 5% 6% 29%	2412
	11th to 20th	Day	21% 10% 3 7% 4 5% 4 3 5% 7% 31%	2389
	21st to end	Day	21% 12% 4 7% 4 4 4 4 6% 6% 30%	2600
May	1st to 10th	Day	28% 12% 3 6% 4 4 4 3 4 6% 26%	6271
	11th to 20th	Day	19% 10% 3 7% 5% 4 5% 4 5% 7% 32%	6318
	21st to end	Day	17% 8% 2 7% 5% 5% 4 3 5% 8% 34%	6948
June	1st to 10th	Day	23% 9% 3 6% 5% 5% 5% 5% 6% 8% 25%	2800
	11th to 20th	Day	18% 9% 2 7% 4 4 4 4 6% 8% 36%	2800
	21st to end	Day	20% 9% 2 8% 5% 5% 4 4 6% 6% 31%	2972
July	1st to 10th	Day	17% 9% 3 7% 5% 5% 5% 5% 6% 8% 30%	6360
	11th to 20th	Day	13% 6% 2 6% 5% 4 5% 4 6% 8% 42%	6360
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	6927
August	1st to 10th	Day	15% 9% 3 8% 5% 5% 5% 5% 7% 7% 32%	4309
	11th to 20th	Day	12% 6% 2 7% 5% 5% 5% 5% 6% 8% 39%	4175
	21st to end	Day	10% 5% 2 6% 5% 4 5% 4 6% 8% 46%	4418
September	1st to 10th	Day	16% 5% 3 6% 5% 4 4 4 5% 8% 42%	2400
	11th to 20th	Day	16% 8% 3 6% 5% 5% 4 4 5% 6% 39%	2400
	21st to end	Day	16% 8% 3 7% 4 3 4 3 5% 7% 39%	2092
October	1st to 10th	Day	18% 9% 2 7% 5% 4 5% 3 5% 7% 35%	2000
	11th to 20th	Day	20% 11% 4 9% 5% 5% 5% 3 5% 7% 26%	2000
	21st to end	Day	20% 16% 3 9% 5% 4 5% 3 5% 6% 24%	2125
November	1st to 10th	Day	21% 17% 4 8% 5% 4 5% 4 5% 5% 21%	1735
	11th to 20th	Day	22% 21% 6% 9% 6% 3 3 3 5% 5% 18%	1680
	21st to end	Day	18% 18% 6% 14% 6% 4 4 3 5% 5% 16%	1680
December	1st to 10th	Day	16% 16% 8% 17% 8% 5% 4 3 4 4 15%	2690
	11th to 20th	Day	21% 16% 6% 18% 6% 5% 4 3 4 3 16%	3076
	21st to end	Day	17% 13% 10% 20% 6% 5% 3 3 4 5% 14%	4070
January	1st to 10th	Night	16% 18% 9% 18% 6% 5% 4 3 3 4 14%	8234
	11th to 20th	Night	19% 16% 7% 15% 6% 5% 3 3 4 4 18%	8234
	21st to end	Night	9% 12% 6% 13% 8% 7% 7% 4 5% 5% 24%	8543
February	1st to 10th	Night	19% 13% 5% 11% 6% 5% 4 3 5% 5% 24%	2730
	11th to 20th	Night	16% 16% 5% 12% 8% 6% 4 3 4 5% 22%	2663
	21st to end	Night	11% 17% 6% 9% 6% 5% 3 3 5% 5% 30%	2170
March	1st to 10th	Night	21% 15% 6% 11% 7% 5% 4 3 4 4 20%	5217
	11th to 20th	Night	19% 14% 5% 9% 5% 5% 4 4 4 6% 25%	5089
	21st to end	Night	24% 17% 7% 10% 5% 4 3 3 3 3 21%	5456
April	1st to 10th	Night	22% 14% 4 9% 5% 4 4 3 5% 6% 25%	2011
	11th to 20th	Night	21% 12% 4 7% 4 4 4 3 5% 6% 31%	1959
	21st to end	Night	24% 12% 3 7% 5% 5% 4 3 4 5% 28%	1800
May	1st to 10th	Night	34% 13% 3 7% 4 4 3 3 4 6% 20%	3686
	11th to 20th	Night	19% 10% 3 9% 5% 5% 5% 3 5% 6% 30%	3596
	21st to end	Night	16% 10% 3 7% 5% 5% 5% 5% 5% 7% 30%	3948
June	1st to 10th	Night	26% 9% 3 7% 5% 4 4 3 4 7% 28%	1600
	11th to 20th	Night	20% 7% 2 6% 4 3 3 3 6% 7% 38%	1600
	21st to end	Night	22% 8% 3 7% 5% 4 4 4 6% 7% 30%	1427
July	1st to 10th	Night	14% 9% 3 9% 6% 6% 6% 5% 7% 9% 25%	3564
	11th to 20th	Night	12% 7% 2 6% 5% 3 5% 4 6% 10% 40%	3620
	21st to end	Night	16% 7% 2 6% 4 4 4 4 7% 9% 37%	3948
August	1st to 10th	Night	16% 8% 3 7% 6% 5% 5% 4 6% 8% 32%	2840
	11th to 20th	Night	14% 7% 2 7% 5% 5% 5% 4 5% 9% 37%	2872
	21st to end	Night	14% 5% 2 5% 4 5% 5% 4 6% 9% 42%	3479
September	1st to 10th	Night	13% 7% 3 7% 5% 4 4 3 6% 8% 42%	2000
	11th to 20th	Night	17% 8% 3 5% 4 4 4 3 5% 6% 42%	2000
	21st to end	Night	18% 6% 3 6% 5% 4 4 4 5% 8% 37%	2305
October	1st to 10th	Night	19% 8% 3 7% 4 4 4 3 6% 6% 37%	2400
	11th to 20th	Night	19% 12% 3 8% 4 4 4 3 6% 7% 30%	2400
	21st to end	Night	26% 13% 3 9% 5% 5% 4 3 4 6% 24%	2714
November	1st to 10th	Night	19% 18% 4 8% 5% 5% 4 3 4 6% 24%	2783
	11th to 20th	Night	23% 19% 4 9% 6% 4 4 4 5% 5% 17%	2940
	21st to end	Night	23% 20% 5% 10% 5% 4 4 4 4 5% 16%	2940
December	1st to 10th	Night	16% 15% 7% 17% 8% 4 4 3 4 5% 18%	4720
	11th to 20th	Night	21% 15% 4 16% 8% 4 3 2 3 4 19%	5353
	21st to end	Night	23% 15% 6% 16% 5% 3 3 3 3 5% 17%	7150

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	73% 7% 11% 7% 2	4691
	11th to 20th	Day	69% 6% 10% 9% 5%	4710
	21st to end	Day	56% 5% 8% 17% 12% 2	5627
February	1st to 10th	Day	63% 5% 11% 13% 8% 1	1890
	11th to 20th	Day	62% 6% 10% 15% 6%	1851
	21st to end	Day	54% 7% 12% 16% 8% 2	1635
March	1st to 10th	Day	63% 5% 10% 14% 9% 1	4831
	11th to 20th	Day	58% 7% 16% 14% 4 1	5090
	21st to end	Day	69% 5% 8% 12% 5% 1	5717
April	1st to 10th	Day	60% 6% 9% 13% 10% 2	2412
	11th to 20th	Day	55% 7% 9% 18% 10% 1	2389
	21st to end	Day	57% 8% 11% 15% 9% 1	2600
May	1st to 10th	Day	61% 7% 11% 15% 5%	6283
	11th to 20th	Day	52% 9% 13% 21% 6%	6322
	21st to end	Day	48% 10% 14% 20% 9%	6948
June	1st to 10th	Day	57% 9% 12% 17% 5% 1	2800
	11th to 20th	Day	49% 7% 14% 21% 9% 1	2800
	21st to end	Day	56% 9% 11% 15% 9% 1	2972
July	1st to 10th	Day	51% 8% 15% 17% 9%	6290
	11th to 20th	Day	40% 8% 16% 27% 9%	6284
	21st to end	Day	39% 9% 19% 26% 6%	6730
August	1st to 10th	Day	51% 10% 12% 20% 7%	4295
	11th to 20th	Day	44% 9% 14% 24% 8%	4214
	21st to end	Day	35% 8% 15% 30% 13%	4418
September	1st to 10th	Day	42% 7% 15% 24% 11%	2400
	11th to 20th	Day	45% 8% 13% 22% 12%	2400
	21st to end	Day	44% 8% 12% 24% 12%	2092
October	1st to 10th	Day	49% 8% 14% 21% 8%	3260
	11th to 20th	Day	50% 8% 11% 22% 8%	3240
	21st to end	Day	51% 6% 15% 19% 8%	3419
November	1st to 10th	Day	62% 7% 11% 15% 5%	1735
	11th to 20th	Day	66% 8% 13% 10% 3	1680
	21st to end	Day	65% 9% 14% 9% 3	1680
December	1st to 10th	Day	63% 8% 10% 17% 3	2690
	11th to 20th	Day	67% 9% 8% 7% 8%	3075
	21st to end	Day	69% 8% 12% 9% 2	4070
January	1st to 10th	Night	71% 7% 9% 11% 2	8234
	11th to 20th	Night	67% 7% 9% 12% 5%	8280
	21st to end	Night	56% 8% 9% 13% 11% 2	8543
February	1st to 10th	Night	63% 6% 9% 13% 8% 1	2730
	11th to 20th	Night	64% 6% 10% 14% 6% 1	2666
	21st to end	Night	57% 5% 11% 18% 8% 1	2170
March	1st to 10th	Night	68% 5% 7% 10% 9% 1	5226
	11th to 20th	Night	59% 7% 12% 15% 7% 1	5090
	21st to end	Night	68% 4 6% 13% 7% 1	5456
April	1st to 10th	Night	61% 7% 10% 12% 9% 2	2011
	11th to 20th	Night	54% 6% 9% 19% 11% 1	1959
	21st to end	Night	58% 7% 9% 14% 11% 1	1800
May	1st to 10th	Night	66% 6% 8% 13% 7%	3691
	11th to 20th	Night	52% 9% 10% 21% 7% 1	3597
	21st to end	Night	50% 9% 16% 20% 4	3949
June	1st to 10th	Night	56% 7% 12% 19% 6%	1600
	11th to 20th	Night	44% 7% 13% 21% 14%	1600
	21st to end	Night	52% 10% 13% 17% 8% 1	1427
July	1st to 10th	Night	51% 10% 15% 18% 5% 1	3525
	11th to 20th	Night	38% 8% 18% 24% 11% 1	3572
	21st to end	Night	42% 9% 16% 26% 7%	3831
August	1st to 10th	Night	48% 9% 15% 23% 5%	2829
	11th to 20th	Night	43% 11% 15% 26% 6%	2899
	21st to end	Night	37% 9% 17% 25% 11% 1	3478
September	1st to 10th	Night	39% 7% 14% 28% 11% 1	2000
	11th to 20th	Night	42% 7% 12% 27% 12% 1	2000
	21st to end	Night	44% 7% 13% 26% 10%	2305
October	1st to 10th	Night	51% 7% 14% 20% 9%	3920
	11th to 20th	Night	43% 10% 12% 25% 10%	3899
	21st to end	Night	51% 7% 13% 20% 9% 1	4374
November	1st to 10th	Night	60% 7% 13% 15% 5%	2783
	11th to 20th	Night	64% 8% 12% 12% 4	2940
	21st to end	Night	65% 9% 14% 10% 2	2940
December	1st to 10th	Night	56% 8% 12% 19% 5%	4720
	11th to 20th	Night	66% 6% 9% 12% 5% 2	5355
	21st to end	Night	69% 6% 12% 11% 3	7150

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	30% 20% 33% 14% 2	430
	11th to 20th	Day	27% 24% 27% 16% 5%	430
	21st to end	Day	19% 20% 40% 19% 2	473
February	1st to 10th	Day	27% 20% 32% 17% 3	430
	11th to 20th	Day	26% 25% 27% 17% 4	426
	21st to end	Day	19% 19% 34% 23% 5% 1	355
March	1st to 10th	Day	21% 18% 38% 19% 3	488
	11th to 20th	Day	19% 21% 33% 22% 5% 1	540
	21st to end	Day	28% 19% 30% 17% 5% 1	594
April	1st to 10th	Day	30% 23% 32% 12% 3	504
	11th to 20th	Day	25% 24% 28% 18% 4 1	492
	21st to end	Day	27% 15% 30% 21% 6% 1	500
May	1st to 10th	Day	31% 15% 27% 19% 5% 3	668
	11th to 20th	Day	21% 11% 30% 25% 11% 2	724
	21st to end	Day	22% 11% 32% 26% 7% 1	790
June	1st to 10th	Day	31% 9% 28% 21% 10% 1	730
	11th to 20th	Day	20% 8% 29% 30% 11% 2	730
	21st to end	Day	24% 9% 24% 29% 13% 1	730
July	1st to 10th	Day	18% 5% 29% 34% 13% 1	720
	11th to 20th	Day	15% 5% 26% 33% 19% 2	718
	21st to end	Day	16% 4 25% 35% 17% 2	795
August	1st to 10th	Day	16% 4 21% 37% 18% 4	574
	11th to 20th	Day	19% 7% 22% 28% 16% 8%	519
	21st to end	Day	13% 8% 24% 35% 16% 4	583
September	1st to 10th	Day	15% 11% 27% 32% 13% 2	530
	11th to 20th	Day	22% 12% 24% 26% 13% 4	530
	21st to end	Day	20% 11% 29% 23% 15% 2	464
October	1st to 10th	Day	20% 12% 29% 25% 11% 2	420
	11th to 20th	Day	25% 16% 25% 22% 10% 2	420
	21st to end	Day	27% 20% 26% 20% 6% 1	462
November	1st to 10th	Day	32% 19% 31% 15% 3 1	425
	11th to 20th	Day	36% 21% 27% 12% 3 1	430
	21st to end	Day	33% 22% 29% 12% 3 1	430
December	1st to 10th	Day	29% 23% 31% 13% 2	430
	11th to 20th	Day	35% 23% 29% 11% 1	430
	21st to end	Day	23% 27% 32% 15% 3	473
January	1st to 10th	Night	27% 23% 33% 16% 2	950
	11th to 20th	Night	26% 20% 32% 18% 4	950
	21st to end	Night	20% 22% 35% 19% 4 1	951
February	1st to 10th	Night	27% 16% 31% 23% 3	840
	11th to 20th	Night	26% 22% 30% 18% 5%	823
	21st to end	Night	19% 18% 33% 24% 7%	692
March	1st to 10th	Night	22% 18% 36% 20% 4	840
	11th to 20th	Night	21% 16% 30% 24% 8%	840
	21st to end	Night	28% 15% 29% 22% 5% 1	870
April	1st to 10th	Night	30% 18% 28% 19% 5%	604
	11th to 20th	Night	26% 15% 29% 23% 6% 1	594
	21st to end	Night	28% 13% 27% 25% 7% 1	600
May	1st to 10th	Night	32% 10% 26% 21% 8% 2	600
	11th to 20th	Night	25% 7% 30% 30% 8% 1	592
	21st to end	Night	22% 8% 36% 26% 7% 1	649
June	1st to 10th	Night	29% 7% 27% 29% 8%	600
	11th to 20th	Night	21% 8% 27% 35% 8% 1	600
	21st to end	Night	22% 6% 27% 34% 10%	427
July	1st to 10th	Night	16% 5% 25% 41% 13%	556
	11th to 20th	Night	15% 4 25% 40% 15% 1	582
	21st to end	Night	17% 5% 24% 38% 14% 1	656
August	1st to 10th	Night	15% 3 25% 39% 16% 1	598
	11th to 20th	Night	19% 6% 23% 34% 17% 2	592
	21st to end	Night	14% 6% 24% 39% 16% 1	660
September	1st to 10th	Night	15% 9% 28% 37% 11% 1	600
	11th to 20th	Night	21% 10% 23% 31% 14% 1	600
	21st to end	Night	22% 10% 31% 28% 8% 2	785
October	1st to 10th	Night	23% 11% 29% 25% 11% 1	800
	11th to 20th	Night	25% 14% 29% 22% 8% 1	800
	21st to end	Night	32% 18% 29% 17% 4	921
November	1st to 10th	Night	30% 21% 29% 15% 4 1	930
	11th to 20th	Night	34% 21% 26% 15% 4 1	950
	21st to end	Night	35% 20% 27% 15% 2	950
December	1st to 10th	Night	31% 22% 32% 12% 3	950
	11th to 20th	Night	31% 27% 29% 12% 1	950
	21st to end	Night	31% 24% 28% 14% 3 1	1045

Page generated at 2026-03-30 03:18:46. Version ac07

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