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 2024-09-14.

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	18% 9% 3 8% 5% 5% 5% 4 6% 7% 31%	101023
	Night	18% 10% 3 8% 5% 5% 5% 4 5% 6% 31%	96942
Transparency	Day	52% 4 14% 21% 9% 1	100770
	Night	54% 4 13% 20% 9% 1	96816
Seeing	Day	22% 13% 29% 23% 10% 2	15826
	Night	22% 10% 31% 28% 8% 1	23761

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% 12% 5% 11% 7% 6% 5% 4 5% 6% 26%	2211
	11th to 20th	Day	13% 11% 5% 13% 6% 5% 5% 4 6% 7% 25%	2520
	21st to end	Day	8% 9% 4 9% 6% 6% 6% 6% 8% 8% 31%	2772
February	1st to 10th	Day	11% 14% 5% 7% 6% 5% 6% 5% 7% 7% 25%	1692
	11th to 20th	Day	15% 11% 5% 10% 6% 5% 6% 4 7% 7% 25%	1677
	21st to end	Day	12% 8% 3 7% 8% 6% 7% 4 6% 7% 30%	1570
March	1st to 10th	Day	18% 11% 4 9% 5% 5% 5% 4 6% 6% 27%	3169
	11th to 20th	Day	17% 16% 5% 11% 6% 5% 5% 4 5% 5% 19%	3480
	21st to end	Day	22% 12% 4 7% 5% 4 5% 3 4 6% 27%	3816
April	1st to 10th	Day	19% 12% 3 8% 6% 6% 5% 4 5% 6% 27%	2276
	11th to 20th	Day	18% 9% 3 7% 5% 4 5% 4 6% 6% 34%	2442
	21st to end	Day	24% 10% 3 6% 4 4 4 3 5% 6% 32%	2470
May	1st to 10th	Day	17% 8% 3 8% 6% 6% 6% 4 6% 7% 29%	4106
	11th to 20th	Day	21% 9% 2 7% 4 4 5% 4 5% 7% 31%	4318
	21st to end	Day	16% 6% 3 8% 5% 6% 6% 5% 7% 8% 30%	5185
June	1st to 10th	Day	21% 9% 2 7% 5% 5% 5% 4 7% 8% 27%	2850
	11th to 20th	Day	18% 7% 2 7% 5% 4 5% 4 6% 7% 34%	2850
	21st to end	Day	22% 10% 3 7% 6% 5% 5% 4 6% 7% 25%	2850
July	1st to 10th	Day	15% 6% 2 8% 5% 6% 6% 5% 7% 10% 30%	4760
	11th to 20th	Day	16% 5% 3 7% 5% 4 5% 5% 7% 8% 35%	4676
	21st to end	Day	15% 6% 2 5% 5% 5% 5% 5% 7% 9% 38%	4814
August	1st to 10th	Day	17% 6% 2 6% 5% 6% 6% 5% 7% 8% 32%	4116
	11th to 20th	Day	16% 8% 3 8% 6% 6% 5% 4 7% 8% 29%	4045
	21st to end	Day	17% 6% 2 6% 4 5% 5% 4 6% 9% 37%	4532
September	1st to 10th	Day	16% 6% 3 6% 4 3 5% 2 6% 7% 41%	2257
	11th to 20th	Day	18% 5% 2 4 4 4 3 3 4 7% 47%	2015
	21st to end	Day	17% 6% 2 6% 5% 3 4 4 5% 8% 40%	1980
October	1st to 10th	Day	16% 9% 2 7% 5% 5% 3 3 5% 7% 37%	1885
	11th to 20th	Day	22% 8% 3 7% 4 4 4 4 5% 6% 32%	1782
	21st to end	Day	25% 9% 4 8% 5% 4 5% 3 5% 7% 25%	1782
November	1st to 10th	Day	19% 11% 3 7% 5% 5% 5% 4 5% 6% 30%	1657
	11th to 20th	Day	20% 9% 2 10% 5% 5% 5% 5% 6% 6% 27%	1520
	21st to end	Day	20% 11% 3 9% 5% 5% 5% 3 5% 7% 26%	1519
December	1st to 10th	Day	21% 12% 4 8% 6% 6% 5% 3 5% 5% 24%	1330
	11th to 20th	Day	20% 12% 4 10% 6% 6% 4 4 5% 6% 24%	1668
	21st to end	Day	20% 13% 4 10% 5% 4 3 3 4 5% 28%	2431
January	1st to 10th	Night	11% 13% 6% 12% 7% 6% 7% 5% 6% 8% 21%	4741
	11th to 20th	Night	14% 12% 5% 10% 7% 6% 5% 4 6% 6% 24%	4440
	21st to end	Night	9% 13% 4 10% 6% 6% 5% 5% 6% 7% 30%	4884
February	1st to 10th	Night	12% 14% 4 8% 6% 6% 5% 4 5% 7% 27%	2486
	11th to 20th	Night	13% 13% 6% 11% 7% 6% 5% 4 5% 6% 24%	2386
	21st to end	Night	13% 13% 3 9% 6% 5% 5% 4 4 4 34%	1884
March	1st to 10th	Night	18% 12% 3 8% 5% 4 6% 4 5% 6% 28%	3670
	11th to 20th	Night	15% 17% 6% 11% 6% 5% 5% 3 4 5% 22%	3479
	21st to end	Night	26% 13% 3 7% 3 3 3 2 4 7% 28%	3816
April	1st to 10th	Night	22% 12% 3 7% 5% 5% 4 3 5% 4 32%	1900
	11th to 20th	Night	20% 9% 2 7% 5% 4 4 4 5% 7% 34%	1688
	21st to end	Night	24% 10% 3 6% 4 5% 4 3 5% 5% 32%	1710
May	1st to 10th	Night	20% 9% 2 6% 4 4 4 4 6% 7% 33%	2834
	11th to 20th	Night	21% 8% 3 7% 5% 5% 5% 4 5% 6% 31%	2608
	21st to end	Night	15% 6% 2 6% 4 4 5% 4 8% 7% 39%	2401
June	1st to 10th	Night	24% 8% 3 6% 4 3 5% 4 4 7% 32%	1330
	11th to 20th	Night	17% 6% 1 5% 5% 4 4 4 8% 8% 37%	1330
	21st to end	Night	23% 8% 4 7% 6% 4 4 3 5% 5% 31%	1330
July	1st to 10th	Night	12% 7% 2 7% 6% 5% 4 4 6% 9% 38%	2210
	11th to 20th	Night	19% 5% 2 6% 4 4 5% 5% 6% 7% 37%	2289
	21st to end	Night	13% 7% 2 6% 4 5% 4 4 6% 8% 42%	2739
August	1st to 10th	Night	19% 7% 3 7% 5% 5% 6% 4 7% 6% 31%	2781
	11th to 20th	Night	13% 6% 3 9% 6% 5% 5% 5% 7% 9% 33%	2782
	21st to end	Night	17% 5% 3 6% 3 4 3 3 4 6% 45%	3124
September	1st to 10th	Night	15% 5% 2 6% 4 4 4 3 6% 8% 44%	1920
	11th to 20th	Night	16% 6% 2 5% 4 4 3 4 6% 6% 45%	2023
	21st to end	Night	18% 5% 2 5% 3 3 4 3 5% 6% 46%	1980
October	1st to 10th	Night	19% 6% 2 5% 4 3 3 3 4 6% 43%	2074
	11th to 20th	Night	20% 9% 3 6% 4 4 5% 3 6% 6% 35%	2173
	21st to end	Night	24% 10% 2 7% 5% 4 4 4 5% 6% 31%	2574
November	1st to 10th	Night	20% 10% 3 5% 6% 4 4 4 5% 6% 32%	2419
	11th to 20th	Night	20% 10% 3 7% 5% 4 4 4 6% 7% 31%	2660
	21st to end	Night	19% 10% 4 9% 6% 5% 5% 4 5% 6% 26%	2660
December	1st to 10th	Night	23% 13% 4 9% 6% 4 3 3 4 5% 24%	2850
	11th to 20th	Night	24% 10% 3 8% 6% 4 5% 4 4 6% 25%	3531
	21st to end	Night	20% 15% 4 8% 5% 4 4 4 5% 6% 26%	5236

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	60% 3 14% 18% 5%	2212
	11th to 20th	Day	59% 3 10% 21% 7%	2520
	21st to end	Day	47% 3 17% 20% 12% 1	2772
February	1st to 10th	Day	56% 5% 11% 17% 10% 1	1692
	11th to 20th	Day	58% 4 12% 18% 7% 1	1685
	21st to end	Day	51% 5% 11% 23% 9% 2	1570
March	1st to 10th	Day	57% 3 12% 15% 11% 3	3173
	11th to 20th	Day	65% 3 11% 13% 6% 1	3480
	21st to end	Day	60% 2 6% 20% 10% 2	3816
April	1st to 10th	Day	56% 4 10% 19% 9% 2	2276
	11th to 20th	Day	48% 3 11% 24% 12% 2	2442
	21st to end	Day	54% 3 8% 20% 12% 3	2470
May	1st to 10th	Day	53% 2 11% 24% 9% 1	4120
	11th to 20th	Day	53% 2 17% 20% 8% 1	4322
	21st to end	Day	50% 5% 12% 20% 12% 1	5185
June	1st to 10th	Day	52% 5% 15% 17% 10% 1	2850
	11th to 20th	Day	49% 4 14% 20% 11% 2	2850
	21st to end	Day	58% 5% 12% 16% 8%	2850
July	1st to 10th	Day	50% 3 18% 20% 8%	4685
	11th to 20th	Day	47% 3 17% 27% 5%	4595
	21st to end	Day	44% 4 18% 26% 8%	4661
August	1st to 10th	Day	49% 5% 18% 22% 7%	4102
	11th to 20th	Day	52% 4 17% 22% 4	4084
	21st to end	Day	46% 3 15% 25% 11%	4532
September	1st to 10th	Day	43% 4 15% 26% 13%	2257
	11th to 20th	Day	40% 3 14% 28% 15%	2015
	21st to end	Day	42% 5% 12% 28% 12%	1980
October	1st to 10th	Day	48% 3 11% 28% 9%	1885
	11th to 20th	Day	53% 4 16% 21% 6%	1782
	21st to end	Day	59% 4 13% 16% 8%	1782
November	1st to 10th	Day	55% 3 12% 22% 8%	1657
	11th to 20th	Day	56% 5% 11% 19% 8%	1520
	21st to end	Day	60% 3 17% 18% 3	1519
December	1st to 10th	Day	61% 3 15% 15% 6%	1330
	11th to 20th	Day	62% 3 9% 18% 9%	1668
	21st to end	Day	62% 3 11% 16% 6% 2	2431
January	1st to 10th	Night	63% 3 15% 15% 4	4741
	11th to 20th	Night	60% 4 10% 20% 6%	4440
	21st to end	Night	54% 4 11% 20% 11% 1	4884
February	1st to 10th	Night	57% 4 11% 16% 10% 1	2486
	11th to 20th	Night	61% 4 9% 16% 8% 1	2389
	21st to end	Night	54% 3 9% 20% 12% 1	1884
March	1st to 10th	Night	57% 4 10% 21% 8% 1	3679
	11th to 20th	Night	66% 2 9% 15% 7% 1	3480
	21st to end	Night	59% 2 5% 21% 11% 2	3816
April	1st to 10th	Night	55% 4 8% 18% 12% 4	1900
	11th to 20th	Night	50% 3 9% 21% 15% 2	1688
	21st to end	Night	55% 3 7% 18% 16% 2	1710
May	1st to 10th	Night	50% 4 14% 21% 11% 1	2840
	11th to 20th	Night	54% 2 12% 24% 7% 1	2609
	21st to end	Night	43% 4 13% 25% 14%	2402
June	1st to 10th	Night	52% 4 11% 22% 9% 1	1330
	11th to 20th	Night	43% 5% 16% 22% 12% 2	1330
	21st to end	Night	55% 5% 12% 17% 9% 1	1330
July	1st to 10th	Night	44% 3 22% 22% 9%	2175
	11th to 20th	Night	47% 4 17% 26% 6%	2247
	21st to end	Night	41% 4 21% 25% 8%	2651
August	1st to 10th	Night	53% 4 16% 23% 5%	2771
	11th to 20th	Night	48% 5% 23% 17% 7%	2809
	21st to end	Night	42% 3 15% 25% 14%	3124
September	1st to 10th	Night	40% 4 14% 30% 12% 1	1920
	11th to 20th	Night	40% 4 14% 27% 14%	2023
	21st to end	Night	40% 5% 13% 27% 15% 1	1980
October	1st to 10th	Night	44% 3 11% 29% 11% 1	2074
	11th to 20th	Night	51% 3 14% 24% 8%	2173
	21st to end	Night	55% 4 13% 20% 8%	2574
November	1st to 10th	Night	53% 4 14% 22% 8%	2419
	11th to 20th	Night	55% 4 13% 18% 10% 1	2660
	21st to end	Night	60% 5% 15% 14% 5% 1	2660
December	1st to 10th	Night	64% 3 11% 18% 4	2850
	11th to 20th	Night	63% 3 10% 18% 7%	3532
	21st to end	Night	61% 3 10% 17% 8% 1	5236

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% 29% 25% 7%	180
	11th to 20th	Day	28% 16% 30% 17% 8%	180
	21st to end	Day	19% 15% 33% 18% 11% 5%	198
February	1st to 10th	Day	23% 14% 30% 25% 7% 1	352
	11th to 20th	Day	17% 16% 39% 23% 5%	372
	21st to end	Day	17% 18% 34% 24% 7%	382
March	1st to 10th	Day	25% 13% 32% 24% 6%	460
	11th to 20th	Day	22% 16% 28% 23% 10% 1	460
	21st to end	Day	25% 15% 27% 22% 9% 2	506
April	1st to 10th	Day	28% 16% 29% 18% 8% 1	460
	11th to 20th	Day	21% 13% 30% 23% 10% 2	452
	21st to end	Day	31% 13% 24% 22% 8% 2	460
May	1st to 10th	Day	26% 16% 26% 23% 8% 1	463
	11th to 20th	Day	27% 14% 26% 22% 9% 3	574
	21st to end	Day	23% 15% 32% 21% 7% 1	735
June	1st to 10th	Day	25% 15% 29% 21% 9% 2	680
	11th to 20th	Day	21% 13% 26% 24% 13% 2	680
	21st to end	Day	26% 8% 31% 23% 11% 1	680
July	1st to 10th	Day	18% 7% 33% 27% 13% 2	670
	11th to 20th	Day	16% 8% 29% 31% 15% 2	623
	21st to end	Day	17% 5% 31% 32% 13% 3	532
August	1st to 10th	Day	18% 9% 28% 28% 13% 4	486
	11th to 20th	Day	17% 8% 26% 29% 17% 3	479
	21st to end	Day	19% 12% 21% 26% 17% 6%	539
September	1st to 10th	Day	16% 12% 27% 26% 15% 4	490
	11th to 20th	Day	21% 11% 25% 24% 13% 6%	463
	21st to end	Day	22% 12% 28% 22% 11% 6%	450
October	1st to 10th	Day	18% 12% 30% 21% 14% 4	402
	11th to 20th	Day	28% 15% 26% 18% 10% 3	360
	21st to end	Day	30% 16% 27% 19% 7% 1	396
November	1st to 10th	Day	28% 16% 27% 21% 7% 1	365
	11th to 20th	Day	25% 16% 30% 20% 7% 1	370
	21st to end	Day	27% 16% 30% 22% 5% 1	369
December	1st to 10th	Day	21% 16% 32% 17% 12% 2	180
	11th to 20th	Day	26% 16% 35% 18% 3 1	180
	21st to end	Day	26% 17% 34% 18% 4 1	198
January	1st to 10th	Night	21% 13% 37% 24% 5%	846
	11th to 20th	Night	26% 13% 32% 22% 6%	760
	21st to end	Night	15% 12% 38% 27% 8%	836
February	1st to 10th	Night	17% 13% 41% 23% 6% 1	760
	11th to 20th	Night	21% 15% 35% 24% 5%	743
	21st to end	Night	22% 11% 35% 27% 4 1	628
March	1st to 10th	Night	19% 10% 39% 29% 4	760
	11th to 20th	Night	22% 13% 32% 24% 8% 1	760
	21st to end	Night	23% 8% 37% 26% 6% 1	836
April	1st to 10th	Night	28% 12% 29% 26% 5%	722
	11th to 20th	Night	24% 12% 31% 26% 7%	564
	21st to end	Night	29% 10% 29% 24% 7%	570
May	1st to 10th	Night	26% 9% 30% 28% 6%	570
	11th to 20th	Night	26% 8% 30% 28% 7% 1	531
	21st to end	Night	21% 9% 34% 29% 6%	411
June	1st to 10th	Night	25% 6% 27% 34% 8% 1	380
	11th to 20th	Night	20% 3 25% 40% 12%	380
	21st to end	Night	23% 7% 27% 31% 12%	380
July	1st to 10th	Night	19% 5% 29% 35% 12%	370
	11th to 20th	Night	15% 5% 27% 40% 13%	368
	21st to end	Night	20% 4 21% 38% 16% 1	416
August	1st to 10th	Night	18% 4 20% 42% 15%	536
	11th to 20th	Night	15% 3 23% 43% 17%	562
	21st to end	Night	11% 6% 28% 37% 17% 2	627
September	1st to 10th	Night	17% 5% 32% 33% 13%	676
	11th to 20th	Night	19% 7% 24% 35% 14% 1	736
	21st to end	Night	21% 8% 27% 31% 13% 1	720
October	1st to 10th	Night	22% 8% 29% 29% 11% 1	720
	11th to 20th	Night	25% 8% 33% 24% 9%	720
	21st to end	Night	28% 11% 33% 22% 6%	792
November	1st to 10th	Night	27% 10% 32% 24% 6% 1	746
	11th to 20th	Night	22% 18% 30% 23% 7% 1	850
	21st to end	Night	24% 14% 32% 25% 5%	850
December	1st to 10th	Night	31% 8% 34% 21% 5% 2	850
	11th to 20th	Night	25% 15% 32% 23% 4	850
	21st to end	Night	27% 16% 30% 22% 4 1	935

Page generated at 2024-09-11 10:00:00. Version ac07

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