McMicking Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the McMicking Point clear sky chart from 2005-11-06 to 2026-06-01.

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% 9% 3 7% 5% 4 4 3 5% 7% 39%	135941
	Night	16% 10% 3 8% 5% 4 4 4 5% 6% 35%	135940
Transparency	Day	44% 8% 18% 21% 8% 1	135650
	Night	49% 7% 15% 19% 8% 1	135809
Seeing	Day	16% 6% 14% 26% 26% 12%	17326
	Night	21% 6% 17% 27% 22% 6%	25635

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	26% 16% 4 11% 6% 6% 5% 4 5% 5% 13%	4125
	11th to 20th	Day	15% 11% 4 9% 5% 5% 4 4 6% 7% 29%	4176
	21st to end	Day	20% 14% 6% 12% 6% 5% 5% 3 4 5% 21%	5402
February	1st to 10th	Day	22% 15% 5% 9% 6% 6% 5% 3 5% 7% 17%	1890
	11th to 20th	Day	21% 13% 5% 9% 5% 4 5% 4 4 5% 24%	1845
	21st to end	Day	17% 14% 4 11% 7% 6% 5% 4 6% 7% 20%	1572
March	1st to 10th	Day	13% 13% 4 10% 7% 6% 6% 5% 6% 8% 20%	4832
	11th to 20th	Day	14% 13% 4 9% 5% 5% 5% 3 5% 7% 30%	5110
	21st to end	Day	17% 13% 4 10% 7% 6% 6% 5% 5% 7% 21%	5713
April	1st to 10th	Day	16% 11% 4 7% 6% 4 6% 5% 7% 8% 26%	2520
	11th to 20th	Day	14% 9% 3 7% 5% 4 6% 5% 6% 8% 32%	2594
	21st to end	Day	14% 9% 3 7% 4 4 5% 4 7% 7% 36%	2751
May	1st to 10th	Day	11% 6% 3 6% 5% 5% 4 3 4 7% 47%	6460
	11th to 20th	Day	9% 6% 3 7% 4 5% 5% 4 6% 9% 42%	6417
	21st to end	Day	14% 8% 3 7% 4 4 4 4 6% 8% 39%	7099
June	1st to 10th	Day	14% 6% 3 6% 5% 4 4 4 6% 8% 40%	3001
	11th to 20th	Day	9% 7% 3 7% 5% 5% 6% 4 5% 7% 42%	3000
	21st to end	Day	8% 6% 2 5% 4 4 5% 4 6% 8% 47%	3000
July	1st to 10th	Day	5% 2 1 3 2 2 3 2 4 5% 71%	6780
	11th to 20th	Day	3 2 1 3 2 2 2 2 3 5% 77%	6780
	21st to end	Day	6% 2 1 2 2 2 3 2 4 6% 71%	6925
August	1st to 10th	Day	3 2 1 3 2 2 2 2 4 6% 73%	4420
	11th to 20th	Day	7% 6% 3 7% 5% 5% 4 4 5% 7% 47%	4156
	21st to end	Day	10% 5% 3 6% 4 4 4 3 5% 5% 51%	4551
September	1st to 10th	Day	7% 5% 2 5% 3 3 4 3 6% 7% 55%	2400
	11th to 20th	Day	11% 6% 3 8% 4 4 4 4 5% 6% 44%	2378
	21st to end	Day	15% 8% 2 6% 4 4 4 3 5% 7% 42%	2116
October	1st to 10th	Day	15% 7% 3 6% 6% 5% 6% 5% 7% 8% 32%	3280
	11th to 20th	Day	25% 11% 3 8% 5% 4 4 3 5% 7% 25%	3261
	21st to end	Day	17% 10% 3 10% 6% 6% 6% 4 6% 7% 25%	3348
November	1st to 10th	Day	25% 12% 4 10% 6% 6% 5% 5% 5% 6% 18%	1648
	11th to 20th	Day	24% 13% 4 7% 6% 6% 5% 4 5% 6% 22%	1680
	21st to end	Day	24% 11% 4 11% 7% 5% 4 3 5% 5% 19%	1680
December	1st to 10th	Day	16% 14% 6% 13% 7% 6% 4 3 4 6% 21%	2700
	11th to 20th	Day	28% 14% 5% 11% 6% 5% 5% 4 4 5% 12%	2756
	21st to end	Day	23% 19% 5% 12% 6% 5% 4 3 5% 5% 12%	3575
January	1st to 10th	Night	26% 16% 5% 11% 6% 6% 5% 4 5% 5% 12%	8770
	11th to 20th	Night	17% 10% 3 7% 3 3 3 3 5% 7% 37%	8719
	21st to end	Night	19% 12% 4 10% 5% 4 4 3 5% 6% 27%	8785
February	1st to 10th	Night	22% 13% 4 9% 6% 5% 5% 4 4 6% 23%	2730
	11th to 20th	Night	18% 12% 4 8% 5% 4 4 4 5% 6% 29%	2662
	21st to end	Night	21% 13% 4 9% 6% 4 4 4 5% 6% 24%	2233
March	1st to 10th	Night	12% 9% 4 9% 7% 6% 7% 5% 7% 8% 25%	5277
	11th to 20th	Night	13% 10% 3 7% 5% 5% 5% 5% 7% 7% 32%	5109
	21st to end	Night	21% 13% 5% 11% 6% 5% 5% 4 5% 5% 20%	5504
April	1st to 10th	Night	17% 11% 4 8% 5% 5% 5% 5% 6% 7% 29%	2100
	11th to 20th	Night	14% 8% 2 7% 6% 5% 6% 4 5% 8% 35%	1972
	21st to end	Night	17% 8% 3 8% 5% 4 4 4 5% 8% 35%	1869
May	1st to 10th	Night	12% 7% 3 6% 3 3 3 2 3 4 53%	3720
	11th to 20th	Night	9% 6% 2 7% 4 4 5% 4 6% 8% 45%	3696
	21st to end	Night	11% 7% 3 8% 5% 6% 6% 5% 7% 8% 35%	4013
June	1st to 10th	Night	13% 8% 2 7% 6% 4 5% 4 5% 5% 41%	1400
	11th to 20th	Night	11% 7% 3 5% 5% 4 4 3 8% 10% 40%	1400
	21st to end	Night	9% 5% 2 4 4 4 4 4 7% 9% 49%	1400
July	1st to 10th	Night	6% 2 1 2 2 2 2 2 3 5% 72%	3180
	11th to 20th	Night	2 2 1 2 2 1 2 2 2 4 80%	3180
	21st to end	Night	5% 3 1 2 2 2 2 2 4 5% 71%	3916
August	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 76%	2730
	11th to 20th	Night	8% 4 3 6% 4 4 4 3 5% 7% 51%	2902
	21st to end	Night	10% 3 1 5% 3 4 4 3 5% 9% 53%	3361
September	1st to 10th	Night	7% 2 1 3 3 3 4 3 5% 6% 63%	2000
	11th to 20th	Night	13% 6% 2 5% 4 4 3 3 4 6% 49%	2019
	21st to end	Night	14% 6% 3 6% 4 4 4 3 5% 6% 45%	2283
October	1st to 10th	Night	12% 6% 3 7% 4 4 4 3 5% 7% 44%	3920
	11th to 20th	Night	22% 8% 3 7% 4 4 4 3 5% 6% 32%	3897
	21st to end	Night	20% 9% 3 8% 5% 5% 4 3 5% 6% 31%	4454
November	1st to 10th	Night	26% 11% 3 8% 5% 6% 5% 4 5% 6% 22%	2870
	11th to 20th	Night	23% 13% 3 8% 5% 5% 4 4 5% 6% 24%	2940
	21st to end	Night	22% 13% 5% 10% 6% 5% 5% 3 5% 5% 21%	2940
December	1st to 10th	Night	17% 11% 4 10% 6% 6% 5% 4 6% 7% 24%	4700
	11th to 20th	Night	26% 17% 5% 12% 5% 5% 5% 3 5% 5% 12%	5666
	21st to end	Night	22% 15% 5% 10% 6% 6% 5% 4 5% 6% 18%	7623

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	72% 9% 7% 9% 2	4125
	11th to 20th	Day	52% 9% 14% 19% 6%	4197
	21st to end	Day	64% 7% 11% 13% 4	5403
February	1st to 10th	Day	66% 9% 11% 10% 4 1	1890
	11th to 20th	Day	61% 10% 10% 14% 5%	1854
	21st to end	Day	62% 9% 12% 11% 5% 1	1572
March	1st to 10th	Day	56% 9% 13% 16% 5%	4832
	11th to 20th	Day	52% 7% 15% 22% 4 1	5110
	21st to end	Day	61% 10% 14% 12% 2	5713
April	1st to 10th	Day	52% 10% 19% 16% 3	2520
	11th to 20th	Day	46% 9% 15% 20% 8% 1	2594
	21st to end	Day	45% 10% 16% 21% 7% 1	2751
May	1st to 10th	Day	38% 6% 17% 27% 11% 1	6460
	11th to 20th	Day	36% 10% 24% 25% 5%	6420
	21st to end	Day	42% 9% 25% 19% 3 1	7100
June	1st to 10th	Day	42% 8% 22% 19% 7% 1	3001
	11th to 20th	Day	41% 8% 22% 23% 5%	3000
	21st to end	Day	35% 8% 24% 23% 9% 1	3000
July	1st to 10th	Day	18% 5% 22% 26% 21% 9%	6706
	11th to 20th	Day	13% 4 20% 34% 27% 2	6699
	21st to end	Day	16% 4 31% 34% 12% 2	6730
August	1st to 10th	Day	15% 5% 19% 44% 16% 2	4403
	11th to 20th	Day	35% 9% 25% 22% 8% 1	4195
	21st to end	Day	35% 6% 20% 29% 10% 1	4550
September	1st to 10th	Day	30% 8% 23% 24% 13% 3	2400
	11th to 20th	Day	40% 10% 16% 21% 12% 1	2378
	21st to end	Day	44% 9% 16% 22% 9%	2116
October	1st to 10th	Day	48% 8% 18% 22% 4	3280
	11th to 20th	Day	59% 7% 13% 17% 5%	3261
	21st to end	Day	56% 9% 15% 13% 7%	3348
November	1st to 10th	Day	65% 9% 12% 10% 3	1648
	11th to 20th	Day	64% 7% 12% 12% 4 1	1680
	21st to end	Day	66% 9% 9% 12% 5%	1680
December	1st to 10th	Day	64% 7% 11% 15% 3	2700
	11th to 20th	Day	72% 9% 10% 7% 2	2759
	21st to end	Day	71% 9% 10% 8% 2	3575
January	1st to 10th	Night	74% 7% 9% 7% 2	8770
	11th to 20th	Night	47% 7% 16% 20% 9%	8760
	21st to end	Night	58% 7% 12% 17% 5%	8785
February	1st to 10th	Night	63% 7% 13% 10% 6% 1	2730
	11th to 20th	Night	56% 8% 13% 15% 6% 1	2664
	21st to end	Night	60% 7% 12% 13% 6% 1	2233
March	1st to 10th	Night	52% 10% 15% 16% 7%	5277
	11th to 20th	Night	47% 8% 15% 25% 4 1	5110
	21st to end	Night	64% 9% 12% 13% 2	5504
April	1st to 10th	Night	53% 9% 16% 18% 4	2100
	11th to 20th	Night	47% 8% 14% 20% 8% 2	1972
	21st to end	Night	48% 8% 15% 20% 9%	1869
May	1st to 10th	Night	36% 5% 13% 31% 14% 1	3717
	11th to 20th	Night	35% 9% 24% 25% 6%	3696
	21st to end	Night	44% 11% 21% 21% 4	4013
June	1st to 10th	Night	44% 6% 17% 24% 7% 2	1400
	11th to 20th	Night	37% 10% 22% 26% 5%	1400
	21st to end	Night	32% 8% 25% 23% 10% 3	1400
July	1st to 10th	Night	17% 5% 18% 33% 16% 10%	3145
	11th to 20th	Night	11% 3 18% 34% 31% 3	3138
	21st to end	Night	17% 3 23% 37% 18% 2	3806
August	1st to 10th	Night	13% 4 16% 37% 26% 3	2722
	11th to 20th	Night	31% 8% 25% 22% 9% 3	2929
	21st to end	Night	29% 8% 16% 34% 12% 1	3361
September	1st to 10th	Night	22% 7% 20% 30% 16% 4	2000
	11th to 20th	Night	36% 8% 14% 22% 16% 4	2019
	21st to end	Night	41% 7% 16% 24% 11% 1	2283
October	1st to 10th	Night	41% 6% 20% 25% 8%	3920
	11th to 20th	Night	52% 5% 16% 21% 5%	3897
	21st to end	Night	53% 7% 15% 17% 8%	4454
November	1st to 10th	Night	63% 8% 12% 13% 3 1	2870
	11th to 20th	Night	61% 6% 14% 12% 5% 2	2940
	21st to end	Night	64% 9% 12% 10% 5% 1	2940
December	1st to 10th	Night	58% 8% 14% 17% 4	4700
	11th to 20th	Night	73% 8% 10% 6% 2	5662
	21st to end	Night	65% 9% 13% 10% 2	7623

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	29% 15% 27% 17% 10% 2	220
	11th to 20th	Day	24% 10% 20% 29% 16% 1	220
	21st to end	Day	28% 7% 22% 23% 16% 3	316
February	1st to 10th	Day	28% 7% 19% 30% 13% 3	430
	11th to 20th	Day	25% 9% 17% 29% 17% 3	425
	21st to end	Day	21% 14% 18% 27% 15% 5%	364
March	1st to 10th	Day	20% 9% 16% 29% 20% 5%	540
	11th to 20th	Day	24% 9% 16% 26% 16% 9%	540
	21st to end	Day	22% 9% 16% 29% 20% 5%	594
April	1st to 10th	Day	14% 12% 17% 26% 22% 10%	540
	11th to 20th	Day	17% 5% 16% 30% 22% 11%	532
	21st to end	Day	16% 6% 17% 26% 24% 10%	540
May	1st to 10th	Day	12% 6% 12% 23% 37% 11%	543
	11th to 20th	Day	14% 5% 13% 23% 32% 14%	568
	21st to end	Day	12% 5% 14% 30% 26% 13%	633
June	1st to 10th	Day	14% 4 13% 30% 28% 10%	731
	11th to 20th	Day	10% 6% 17% 35% 26% 7%	730
	21st to end	Day	8% 3 13% 30% 31% 16%	730
July	1st to 10th	Day	7% 2 12% 27% 34% 18%	721
	11th to 20th	Day	5% 1 10% 28% 37% 19%	718
	21st to end	Day	3 2 7% 25% 36% 28%	600
August	1st to 10th	Day	6% 2 6% 19% 35% 32%	527
	11th to 20th	Day	4 1 4 20% 41% 30%	517
	21st to end	Day	9% 2 7% 24% 38% 21%	583
September	1st to 10th	Day	11% 1 6% 22% 42% 18%	530
	11th to 20th	Day	13% 2 8% 22% 37% 17%	530
	21st to end	Day	16% 4 13% 26% 30% 12%	530
October	1st to 10th	Day	19% 4 14% 23% 26% 14%	530
	11th to 20th	Day	25% 7% 14% 22% 22% 10%	530
	21st to end	Day	26% 8% 20% 26% 14% 5%	472
November	1st to 10th	Day	29% 6% 21% 27% 15% 1	220
	11th to 20th	Day	26% 11% 15% 25% 17% 6%	220
	21st to end	Day	27% 9% 23% 25% 10% 6%	220
December	1st to 10th	Day	29% 11% 20% 18% 19% 3	220
	11th to 20th	Day	35% 12% 22% 19% 11%	220
	21st to end	Day	36% 12% 20% 25% 7%	242
January	1st to 10th	Night	32% 10% 23% 21% 12% 2	950
	11th to 20th	Night	29% 7% 16% 26% 20% 2	939
	21st to end	Night	28% 6% 15% 25% 21% 4	924
February	1st to 10th	Night	27% 10% 18% 26% 16% 3	840
	11th to 20th	Night	25% 7% 20% 27% 18% 3	824
	21st to end	Night	27% 12% 21% 22% 14% 5%	692
March	1st to 10th	Night	23% 9% 17% 26% 20% 5%	840
	11th to 20th	Night	24% 8% 19% 25% 19% 5%	840
	21st to end	Night	24% 10% 18% 25% 20% 4	924
April	1st to 10th	Night	20% 8% 19% 25% 23% 5%	840
	11th to 20th	Night	17% 5% 23% 27% 20% 7%	724
	21st to end	Night	19% 5% 23% 32% 16% 5%	609
May	1st to 10th	Night	11% 4 21% 33% 26% 5%	420
	11th to 20th	Night	11% 6% 19% 28% 29% 8%	414
	21st to end	Night	12% 6% 19% 32% 25% 6%	455
June	1st to 10th	Night	15% 5% 20% 30% 27% 3	400
	11th to 20th	Night	14% 4 20% 40% 18% 4	400
	21st to end	Night	9% 4 19% 32% 26% 11%	400
July	1st to 10th	Night	10% 1 16% 34% 34% 5%	390
	11th to 20th	Night	6% 3 17% 36% 32% 6%	388
	21st to end	Night	5% 3 14% 34% 35% 10%	438
August	1st to 10th	Night	5% 1 11% 31% 42% 10%	467
	11th to 20th	Night	5% 2 6% 25% 47% 14%	594
	21st to end	Night	9% 2 12% 30% 39% 9%	724
September	1st to 10th	Night	8% 2 8% 31% 36% 15%	800
	11th to 20th	Night	14% 3 8% 25% 32% 18%	800
	21st to end	Night	17% 3 12% 28% 31% 10%	800
October	1st to 10th	Night	17% 4 11% 26% 28% 15%	800
	11th to 20th	Night	23% 4 13% 25% 24% 10%	800
	21st to end	Night	25% 6% 18% 28% 19% 5%	880
November	1st to 10th	Night	31% 7% 18% 25% 18% 2	820
	11th to 20th	Night	28% 9% 20% 24% 16% 3	840
	21st to end	Night	28% 8% 21% 24% 15% 5%	840
December	1st to 10th	Night	28% 7% 17% 24% 20% 3	840
	11th to 20th	Night	31% 10% 24% 24% 11% 1	934
	21st to end	Night	30% 10% 24% 25% 9% 1	1045

Page generated at 2026-05-28 22:53:31. Version ac07

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