Carmacks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carmacks clear sky chart from 2005-11-06 to 2025-04-11.

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	7% 10% 4 12% 8% 7% 7% 5% 7% 8% 25%	115405
	Night	5% 11% 5% 13% 9% 8% 7% 6% 8% 8% 21%	121512
Transparency	Day	54% 3 15% 20% 7%	115090
	Night	57% 3 13% 19% 7% 1	121474
Seeing	Day	15% 7% 21% 29% 21% 8%	17569
	Night	11% 6% 17% 33% 27% 7%	23861

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	1 7% 5% 20% 10% 10% 9% 5% 8% 11% 14%	1815
	11th to 20th	Day	2 11% 5% 14% 11% 9% 8% 6% 9% 11% 14%	2245
	21st to end	Day	1 9% 5% 15% 10% 9% 8% 6% 8% 9% 20%	2875
February	1st to 10th	Day	1 10% 6% 14% 9% 9% 9% 6% 8% 9% 19%	1377
	11th to 20th	Day	4 11% 4 14% 10% 9% 7% 5% 8% 9% 18%	1496
	21st to end	Day	1 10% 6% 13% 10% 9% 8% 7% 6% 8% 21%	1458
March	1st to 10th	Day	1 7% 4 19% 12% 8% 7% 5% 6% 7% 25%	4311
	11th to 20th	Day	2 12% 6% 17% 10% 8% 7% 5% 6% 7% 21%	4792
	21st to end	Day	1 6% 5% 14% 7% 7% 6% 5% 8% 9% 32%	5864
April	1st to 10th	Day	3 12% 5% 14% 7% 6% 6% 6% 6% 9% 26%	2480
	11th to 20th	Day	4 13% 4 11% 7% 6% 6% 5% 6% 7% 31%	2628
	21st to end	Day	5% 11% 4 10% 8% 7% 6% 5% 7% 7% 30%	2712
May	1st to 10th	Day	6% 10% 4 10% 7% 6% 5% 4 6% 8% 34%	5060
	11th to 20th	Day	4 7% 3 8% 7% 7% 8% 7% 9% 10% 30%	5013
	21st to end	Day	7% 9% 4 10% 7% 7% 7% 5% 8% 9% 28%	6163
June	1st to 10th	Day	9% 9% 4 11% 9% 7% 8% 5% 7% 7% 26%	3420
	11th to 20th	Day	10% 11% 5% 11% 8% 7% 6% 5% 7% 8% 23%	3420
	21st to end	Day	12% 8% 3 10% 8% 7% 8% 6% 8% 9% 22%	3420
July	1st to 10th	Day	12% 9% 4 11% 8% 8% 8% 6% 8% 7% 20%	5700
	11th to 20th	Day	10% 8% 4 10% 7% 8% 7% 6% 7% 9% 24%	5579
	21st to end	Day	12% 8% 4 10% 7% 6% 7% 5% 8% 9% 25%	5679
August	1st to 10th	Day	8% 7% 3 8% 5% 5% 6% 4 6% 8% 39%	4990
	11th to 20th	Day	16% 9% 3 8% 6% 6% 5% 5% 7% 9% 27%	4528
	21st to end	Day	14% 10% 4 9% 7% 7% 7% 5% 7% 9% 20%	4873
September	1st to 10th	Day	12% 11% 3 11% 7% 6% 7% 5% 6% 9% 24%	2365
	11th to 20th	Day	10% 8% 3 8% 7% 7% 6% 5% 7% 8% 31%	2280
	21st to end	Day	13% 10% 4 9% 6% 7% 6% 5% 6% 8% 27%	2013
October	1st to 10th	Day	7% 10% 3 9% 6% 7% 6% 5% 9% 9% 29%	3170
	11th to 20th	Day	6% 11% 4 9% 6% 6% 7% 5% 6% 8% 30%	2732
	21st to end	Day	7% 18% 8% 15% 9% 6% 6% 4 6% 6% 16%	2723
November	1st to 10th	Day	4 16% 9% 15% 9% 7% 8% 5% 6% 6% 16%	1292
	11th to 20th	Day	4 17% 8% 14% 10% 9% 7% 6% 7% 5% 13%	1200
	21st to end	Day	4 14% 7% 15% 10% 7% 8% 10% 7% 6% 14%	950
December	1st to 10th	Day	4 11% 5% 16% 8% 6% 5% 6% 10% 10% 17%	1300
	11th to 20th	Day	2 9% 5% 18% 11% 7% 9% 8% 10% 9% 11%	1502
	21st to end	Day	2 12% 6% 16% 12% 9% 7% 5% 8% 9% 13%	1980
January	1st to 10th	Night	3 9% 5% 16% 11% 11% 9% 7% 8% 9% 13%	8146
	11th to 20th	Night	3 11% 6% 13% 8% 7% 7% 6% 10% 12% 18%	7681
	21st to end	Night	3 10% 5% 16% 11% 10% 9% 7% 7% 9% 15%	8080
February	1st to 10th	Night	2 9% 6% 15% 11% 8% 7% 6% 7% 9% 21%	3020
	11th to 20th	Night	2 10% 5% 14% 9% 8% 7% 6% 7% 9% 23%	2791
	21st to end	Night	1 8% 5% 11% 8% 8% 8% 5% 7% 8% 30%	2170
March	1st to 10th	Night	1 6% 3 15% 10% 8% 7% 6% 8% 9% 27%	5563
	11th to 20th	Night	2 13% 6% 14% 9% 7% 7% 5% 7% 7% 22%	5172
	21st to end	Night	1 8% 5% 13% 7% 8% 7% 5% 8% 8% 29%	5085
April	1st to 10th	Night	2 11% 4 12% 8% 5% 5% 5% 7% 9% 32%	1917
	11th to 20th	Night	3 9% 4 12% 7% 7% 7% 6% 8% 6% 31%	1507
	21st to end	Night	4 8% 4 9% 6% 6% 6% 7% 8% 8% 34%	1466
May	1st to 10th	Night	3 6% 3 8% 6% 6% 7% 6% 10% 11% 35%	1900
	11th to 20th	Night	5% 6% 2 8% 6% 5% 7% 7% 9% 9% 35%	1882
	21st to end	Night	6% 7% 3 8% 5% 7% 7% 6% 9% 9% 32%	1410
June	1st to 10th	Night	8% 9% 3 7% 6% 6% 9% 5% 10% 9% 29%	760
	11th to 20th	Night	8% 8% 3 11% 8% 6% 7% 7% 9% 8% 25%	760
	21st to end	Night	11% 8% 5% 10% 8% 6% 8% 6% 11% 8% 20%	760
July	1st to 10th	Night	12% 11% 3 10% 7% 7% 6% 6% 7% 9% 22%	1260
	11th to 20th	Night	8% 6% 3 9% 5% 7% 6% 7% 10% 10% 30%	1379
	21st to end	Night	14% 10% 3 9% 6% 6% 6% 6% 8% 10% 23%	1872
August	1st to 10th	Night	7% 5% 3 7% 5% 5% 6% 5% 8% 7% 42%	1941
	11th to 20th	Night	16% 9% 3 6% 5% 4 6% 6% 7% 9% 29%	2310
	21st to end	Night	9% 9% 5% 11% 7% 7% 7% 5% 8% 8% 21%	2794
September	1st to 10th	Night	10% 9% 3 12% 7% 7% 7% 5% 7% 8% 24%	1814
	11th to 20th	Night	7% 6% 3 9% 7% 8% 7% 6% 7% 10% 33%	1900
	21st to end	Night	11% 12% 4 10% 6% 7% 7% 4 7% 7% 25%	2165
October	1st to 10th	Night	7% 9% 4 9% 6% 6% 6% 5% 8% 10% 30%	3800
	11th to 20th	Night	7% 13% 4 10% 7% 6% 5% 5% 7% 8% 28%	4193
	21st to end	Night	6% 18% 6% 17% 9% 6% 6% 4 6% 7% 15%	4835
November	1st to 10th	Night	6% 15% 6% 16% 8% 7% 7% 5% 5% 6% 18%	3005
	11th to 20th	Night	3 17% 8% 19% 11% 8% 7% 4 5% 5% 13%	3200
	21st to end	Night	5% 15% 6% 15% 11% 8% 8% 8% 7% 4 13%	3428
December	1st to 10th	Night	5% 15% 6% 14% 9% 7% 7% 6% 8% 9% 14%	5880
	11th to 20th	Night	2 11% 6% 18% 11% 8% 9% 6% 9% 9% 11%	6690
	21st to end	Night	4 13% 7% 16% 12% 8% 8% 5% 7% 7% 13%	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	61% 2 8% 15% 11% 2	1815
	11th to 20th	Day	59% 5% 12% 13% 12%	2260
	21st to end	Day	56% 4 11% 14% 10% 4	2875
February	1st to 10th	Day	55% 4 9% 19% 12% 1	1377
	11th to 20th	Day	60% 4 12% 14% 10%	1503
	21st to end	Day	57% 4 14% 18% 7%	1458
March	1st to 10th	Day	59% 1 8% 25% 6%	4311
	11th to 20th	Day	59% 3 10% 17% 11%	4792
	21st to end	Day	45% 2 19% 22% 11% 1	5864
April	1st to 10th	Day	53% 4 16% 21% 6%	2480
	11th to 20th	Day	50% 3 14% 22% 10%	2628
	21st to end	Day	49% 3 14% 24% 9%	2712
May	1st to 10th	Day	47% 2 10% 31% 9%	5060
	11th to 20th	Day	46% 1 9% 31% 13%	5016
	21st to end	Day	51% 2 10% 25% 13%	6164
June	1st to 10th	Day	56% 2 11% 23% 7% 1	3420
	11th to 20th	Day	59% 2 11% 22% 5%	3420
	21st to end	Day	56% 3 16% 21% 3	3420
July	1st to 10th	Day	58% 2 20% 15% 4 1	5611
	11th to 20th	Day	54% 3 22% 18% 3	5480
	21st to end	Day	53% 2 23% 19% 2	5499
August	1st to 10th	Day	43% 3 22% 20% 10% 2	4971
	11th to 20th	Day	54% 3 19% 21% 3	4573
	21st to end	Day	58% 2 23% 17% 1	4872
September	1st to 10th	Day	57% 3 19% 18% 3	2365
	11th to 20th	Day	49% 3 23% 22% 2	2280
	21st to end	Day	55% 2 19% 21% 4	2013
October	1st to 10th	Day	49% 4 20% 23% 4	3170
	11th to 20th	Day	49% 3 18% 27% 3	2732
	21st to end	Day	67% 4 13% 13% 2	2723
November	1st to 10th	Day	63% 5% 13% 17% 2	1292
	11th to 20th	Day	69% 4 13% 12% 3	1200
	21st to end	Day	62% 5% 13% 15% 5%	950
December	1st to 10th	Day	56% 9% 22% 10% 4	1300
	11th to 20th	Day	65% 3 7% 12% 12%	1504
	21st to end	Day	64% 5% 11% 16% 5%	1980
January	1st to 10th	Night	63% 4 8% 12% 12%	8146
	11th to 20th	Night	54% 4 11% 19% 10% 4	7728
	21st to end	Night	61% 4 8% 16% 7% 2	8080
February	1st to 10th	Night	56% 5% 8% 19% 12% 1	3020
	11th to 20th	Night	53% 5% 11% 21% 9% 1	2795
	21st to end	Night	49% 4 16% 20% 11%	2170
March	1st to 10th	Night	51% 1 10% 27% 10%	5563
	11th to 20th	Night	58% 2 8% 22% 10% 1	5174
	21st to end	Night	48% 3 15% 22% 13% 1	5085
April	1st to 10th	Night	47% 3 18% 22% 8% 1	1917
	11th to 20th	Night	48% 3 14% 26% 9% 1	1507
	21st to end	Night	44% 2 16% 28% 9%	1466
May	1st to 10th	Night	39% 2 12% 37% 10%	1900
	11th to 20th	Night	44% 2 11% 30% 14%	1882
	21st to end	Night	44% 1 11% 28% 14% 1	1410
June	1st to 10th	Night	47% 3 14% 28% 7% 1	760
	11th to 20th	Night	52% 5% 12% 25% 5% 1	760
	21st to end	Night	54% 4 16% 21% 5%	760
July	1st to 10th	Night	56% 3 20% 17% 3 1	1240
	11th to 20th	Night	43% 2 26% 23% 5%	1355
	21st to end	Night	55% 2 24% 17% 2	1813
August	1st to 10th	Night	37% 4 25% 21% 13% 1	1935
	11th to 20th	Night	50% 3 19% 26% 2	2331
	21st to end	Night	57% 2 18% 22% 1	2794
September	1st to 10th	Night	57% 3 19% 19% 2	1814
	11th to 20th	Night	46% 3 24% 23% 4	1900
	21st to end	Night	56% 3 17% 19% 5%	2165
October	1st to 10th	Night	48% 3 17% 28% 3	3800
	11th to 20th	Night	53% 2 14% 27% 3	4193
	21st to end	Night	66% 5% 16% 11% 2	4835
November	1st to 10th	Night	64% 4 15% 14% 3	3005
	11th to 20th	Night	71% 3 10% 12% 3	3200
	21st to end	Night	66% 4 11% 16% 3	3428
December	1st to 10th	Night	62% 5% 17% 13% 2	5880
	11th to 20th	Night	64% 5% 12% 12% 6% 1	6687
	21st to end	Night	66% 4 10% 12% 7% 2	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	5% 3 12% 30% 41% 9%	100
	11th to 20th	Day	11% 1 12% 37% 18% 21%	100
	21st to end	Day	9% 6% 19% 33% 22% 11%	195
February	1st to 10th	Day	6% 3 17% 38% 25% 11%	377
	11th to 20th	Day	9% 5% 16% 35% 22% 13%	395
	21st to end	Day	6% 7% 23% 37% 22% 5%	331
March	1st to 10th	Day	6% 9% 23% 27% 23% 12%	400
	11th to 20th	Day	7% 9% 26% 31% 20% 9%	400
	21st to end	Day	7% 7% 26% 29% 21% 10%	525
April	1st to 10th	Day	12% 11% 25% 29% 18% 5%	580
	11th to 20th	Day	12% 10% 24% 28% 21% 5%	642
	21st to end	Day	12% 10% 22% 32% 17% 8%	650
May	1st to 10th	Day	17% 13% 28% 26% 12% 4	653
	11th to 20th	Day	13% 10% 27% 28% 15% 7%	675
	21st to end	Day	14% 8% 27% 27% 19% 5%	915
June	1st to 10th	Day	15% 6% 19% 31% 24% 6%	870
	11th to 20th	Day	17% 6% 17% 31% 22% 7%	870
	21st to end	Day	16% 5% 16% 28% 25% 10%	870
July	1st to 10th	Day	14% 5% 17% 29% 26% 8%	856
	11th to 20th	Day	18% 6% 18% 28% 22% 8%	783
	21st to end	Day	19% 3 14% 29% 26% 8%	739
August	1st to 10th	Day	15% 4 23% 29% 20% 8%	676
	11th to 20th	Day	23% 7% 24% 26% 16% 4	665
	21st to end	Day	18% 6% 22% 31% 19% 4	748
September	1st to 10th	Day	21% 10% 20% 19% 20% 9%	566
	11th to 20th	Day	17% 7% 21% 26% 21% 8%	490
	21st to end	Day	23% 12% 22% 21% 14% 6%	425
October	1st to 10th	Day	18% 11% 28% 21% 15% 7%	390
	11th to 20th	Day	21% 11% 21% 23% 18% 8%	390
	21st to end	Day	16% 6% 16% 29% 24% 9%	410
November	1st to 10th	Day	17% 6% 22% 28% 23% 6%	200
	11th to 20th	Day	10% 5% 12% 37% 28% 9%	200
	21st to end	Day	9% 6% 14% 34% 23% 14%	173
December	1st to 10th	Day	8% 4 15% 34% 28% 11%	100
	11th to 20th	Day	14% 1 15% 32% 25% 13%	100
	21st to end	Day	5% 6% 17% 25% 29% 17%	110
January	1st to 10th	Night	6% 5% 13% 35% 32% 9%	1100
	11th to 20th	Night	11% 5% 14% 41% 24% 4	915
	21st to end	Night	10% 5% 22% 37% 21% 5%	990
February	1st to 10th	Night	6% 4 14% 42% 28% 6%	900
	11th to 20th	Night	6% 6% 18% 39% 25% 6%	884
	21st to end	Night	6% 5% 19% 42% 24% 5%	743
March	1st to 10th	Night	6% 7% 20% 33% 28% 6%	842
	11th to 20th	Night	6% 6% 23% 33% 26% 7%	690
	21st to end	Night	6% 6% 20% 30% 31% 8%	660
April	1st to 10th	Night	8% 5% 20% 33% 27% 7%	600
	11th to 20th	Night	7% 5% 19% 34% 29% 6%	564
	21st to end	Night	8% 7% 15% 29% 35% 7%	556
May	1st to 10th	Night	13% 10% 17% 28% 28% 4	380
	11th to 20th	Night	13% 9% 23% 29% 26% 1	374
	21st to end	Night	8% 5% 27% 27% 30% 3	209
June	1st to 10th	Night	13% 7% 19% 27% 28% 6%	190
	11th to 20th	Night	15% 6% 13% 29% 34% 3	190
	21st to end	Night	14% 7% 15% 23% 32% 8%	190
July	1st to 10th	Night	14% 2 15% 30% 37% 3	185
	11th to 20th	Night	17% 4 17% 23% 30% 9%	184
	21st to end	Night	17% 4 13% 24% 35% 6%	300
August	1st to 10th	Night	12% 5% 18% 29% 32% 5%	400
	11th to 20th	Night	20% 7% 17% 26% 24% 7%	564
	21st to end	Night	15% 4 15% 29% 31% 6%	627
September	1st to 10th	Night	18% 9% 16% 25% 25% 8%	570
	11th to 20th	Night	12% 7% 17% 33% 26% 5%	570
	21st to end	Night	19% 9% 16% 26% 22% 7%	716
October	1st to 10th	Night	19% 10% 18% 27% 21% 5%	760
	11th to 20th	Night	20% 7% 12% 30% 26% 5%	798
	21st to end	Night	14% 5% 13% 36% 24% 7%	946
November	1st to 10th	Night	15% 5% 14% 36% 24% 7%	880
	11th to 20th	Night	10% 3 17% 35% 29% 7%	900
	21st to end	Night	14% 4 18% 30% 25% 8%	1074
December	1st to 10th	Night	12% 4 15% 37% 25% 7%	1100
	11th to 20th	Night	12% 3 15% 37% 27% 7%	1100
	21st to end	Night	9% 4 12% 35% 28% 11%	1210

Page generated at 2025-04-08 05:17:29. Version ac07

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