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 2025-02-06.

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	14% 9% 3 7% 5% 4 4 3 5% 7% 39%	112103
	Night	17% 10% 3 8% 5% 4 4 4 5% 6% 34%	114816
Transparency	Day	45% 8% 17% 21% 8% 1	111853
	Night	50% 8% 15% 19% 8% 1	114712
Seeing	Day	16% 5% 13% 26% 27% 13%	15589
	Night	21% 6% 17% 27% 23% 6%	23988

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% 15% 5% 10% 6% 6% 5% 4 5% 5% 13%	3179
	11th to 20th	Day	15% 13% 5% 10% 6% 5% 4 4 6% 7% 25%	3202
	21st to end	Day	21% 15% 5% 12% 5% 5% 5% 3 4 5% 20%	4165
February	1st to 10th	Day	23% 15% 5% 9% 5% 6% 5% 3 5% 7% 17%	1756
	11th to 20th	Day	22% 13% 5% 9% 5% 4 4 4 4 6% 24%	1665
	21st to end	Day	17% 14% 4 11% 7% 6% 5% 4 6% 7% 21%	1426
March	1st to 10th	Day	11% 12% 4 10% 7% 6% 7% 5% 7% 10% 20%	3283
	11th to 20th	Day	13% 10% 3 7% 4 4 5% 3 6% 7% 38%	3490
	21st to end	Day	17% 12% 4 9% 6% 5% 5% 4 5% 6% 26%	3903
April	1st to 10th	Day	17% 11% 4 7% 6% 5% 6% 5% 6% 8% 25%	2280
	11th to 20th	Day	15% 10% 3 7% 5% 4 6% 5% 6% 7% 32%	2344
	21st to end	Day	15% 10% 3 7% 5% 4 5% 4 7% 8% 33%	2489
May	1st to 10th	Day	13% 6% 2 5% 4 4 4 3 5% 7% 46%	4420
	11th to 20th	Day	8% 4 2 5% 4 4 5% 4 6% 11% 48%	4377
	21st to end	Day	18% 10% 3 7% 4 4 4 3 5% 7% 35%	4840
June	1st to 10th	Day	14% 7% 3 6% 5% 4 4 4 6% 8% 39%	2850
	11th to 20th	Day	9% 7% 2 7% 5% 5% 6% 4 5% 8% 43%	2850
	21st to end	Day	8% 5% 2 5% 5% 4 5% 4 6% 8% 47%	2850
July	1st to 10th	Day	4 3 1 3 2 2 2 2 3 4 74%	4740
	11th to 20th	Day	3 2 1 3 2 2 2 2 3 5% 75%	4740
	21st to end	Day	8% 3 1 3 2 2 2 2 4 6% 68%	4827
August	1st to 10th	Day	3 2 1 3 2 2 2 2 4 6% 74%	4284
	11th to 20th	Day	7% 6% 3 7% 5% 5% 4 4 5% 7% 48%	4026
	21st to end	Day	11% 5% 3 7% 4 4 4 3 5% 5% 51%	4411
September	1st to 10th	Day	7% 5% 2 5% 3 4 4 3 6% 7% 55%	2280
	11th to 20th	Day	11% 6% 3 8% 4 4 4 4 5% 7% 44%	2259
	21st to end	Day	15% 8% 2 6% 4 4 4 3 5% 7% 41%	2010
October	1st to 10th	Day	15% 7% 3 6% 6% 5% 6% 5% 7% 8% 33%	3180
	11th to 20th	Day	25% 11% 3 9% 5% 4 4 3 5% 7% 25%	3161
	21st to end	Day	16% 10% 3 10% 6% 6% 6% 4 6% 8% 25%	3245
November	1st to 10th	Day	26% 12% 4 9% 6% 5% 5% 4 5% 6% 18%	1568
	11th to 20th	Day	23% 13% 4 8% 6% 6% 5% 4 5% 6% 23%	1600
	21st to end	Day	24% 12% 4 11% 7% 5% 4 3 5% 5% 19%	1600
December	1st to 10th	Day	16% 14% 6% 13% 7% 6% 4 3 4 6% 22%	2620
	11th to 20th	Day	28% 14% 5% 11% 6% 5% 5% 4 4 6% 13%	2685
	21st to end	Day	23% 19% 5% 12% 6% 5% 4 3 5% 5% 12%	3498
January	1st to 10th	Night	25% 16% 5% 11% 6% 6% 5% 4 5% 5% 13%	6766
	11th to 20th	Night	17% 10% 3 8% 4 4 4 4 6% 8% 34%	6693
	21st to end	Night	22% 12% 4 9% 5% 4 5% 3 4 5% 26%	6794
February	1st to 10th	Night	23% 13% 4 9% 6% 5% 4 4 4 6% 22%	2535
	11th to 20th	Night	18% 13% 4 8% 5% 4 4 4 5% 6% 29%	2402
	21st to end	Night	22% 12% 4 9% 5% 4 4 4 5% 6% 25%	2027
March	1st to 10th	Night	13% 10% 4 9% 7% 7% 7% 5% 7% 8% 23%	3587
	11th to 20th	Night	13% 7% 3 5% 4 4 5% 4 7% 7% 40%	3489
	21st to end	Night	20% 13% 5% 11% 6% 5% 5% 4 5% 5% 24%	3750
April	1st to 10th	Night	18% 11% 4 7% 5% 5% 4 5% 6% 7% 28%	1900
	11th to 20th	Night	15% 9% 3 7% 6% 4 5% 4 5% 7% 35%	1782
	21st to end	Night	18% 8% 4 8% 5% 5% 4 4 4 7% 32%	1691
May	1st to 10th	Night	12% 7% 2 5% 3 4 4 3 4 5% 51%	2540
	11th to 20th	Night	6% 4 2 6% 4 4 5% 3 5% 7% 54%	2516
	21st to end	Night	14% 8% 3 8% 5% 6% 5% 4 6% 8% 34%	2730
June	1st to 10th	Night	14% 8% 2 8% 6% 4 5% 4 5% 5% 39%	1330
	11th to 20th	Night	11% 7% 3 5% 5% 4 4 4 8% 10% 39%	1330
	21st to end	Night	8% 5% 2 4 3 4 4 4 7% 9% 50%	1330
July	1st to 10th	Night	5% 2 1 2 2 2 3 3 3 5% 73%	2220
	11th to 20th	Night	3 2 1 3 2 1 2 2 2 5% 77%	2220
	21st to end	Night	8% 4 1 3 2 2 2 3 4 4 68%	2723
August	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 76%	2646
	11th to 20th	Night	8% 4 2 6% 4 4 4 3 5% 7% 52%	2812
	21st to end	Night	10% 3 1 5% 3 5% 4 3 5% 9% 52%	3259
September	1st to 10th	Night	7% 3 1 3 3 3 3 3 4 7% 63%	1900
	11th to 20th	Night	13% 6% 2 5% 4 4 3 3 4 6% 48%	1918
	21st to end	Night	14% 6% 3 6% 5% 4 5% 3 5% 6% 45%	2169
October	1st to 10th	Night	13% 6% 3 7% 4 4 4 4 5% 7% 44%	3800
	11th to 20th	Night	22% 8% 3 7% 4 4 4 3 5% 6% 31%	3777
	21st to end	Night	20% 9% 3 8% 5% 5% 4 3 5% 6% 31%	4315
November	1st to 10th	Night	26% 11% 3 8% 5% 6% 5% 4 5% 5% 22%	2730
	11th to 20th	Night	23% 12% 3 7% 5% 5% 4 4 5% 6% 25%	2800
	21st to end	Night	21% 13% 5% 10% 6% 5% 5% 3 5% 5% 21%	2800
December	1st to 10th	Night	16% 11% 4 10% 6% 6% 5% 4 6% 7% 24%	4560
	11th to 20th	Night	26% 17% 5% 12% 5% 5% 5% 3 5% 5% 11%	5517
	21st to end	Night	22% 15% 5% 10% 6% 6% 5% 4 5% 5% 18%	7458

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% 10% 7% 10% 3	3179
	11th to 20th	Day	54% 10% 17% 14% 4	3223
	21st to end	Day	65% 8% 12% 12% 3	4165
February	1st to 10th	Day	67% 9% 11% 9% 4 1	1756
	11th to 20th	Day	61% 10% 11% 13% 5%	1674
	21st to end	Day	61% 8% 12% 12% 6% 1	1426
March	1st to 10th	Day	51% 12% 14% 17% 6%	3283
	11th to 20th	Day	44% 8% 17% 26% 4 1	3490
	21st to end	Day	55% 11% 16% 14% 3	3903
April	1st to 10th	Day	53% 11% 18% 15% 3	2280
	11th to 20th	Day	48% 9% 14% 19% 8% 2	2344
	21st to end	Day	47% 10% 15% 20% 7% 1	2489
May	1st to 10th	Day	38% 7% 17% 26% 11% 1	4420
	11th to 20th	Day	27% 11% 27% 27% 7%	4380
	21st to end	Day	48% 10% 21% 17% 3	4841
June	1st to 10th	Day	44% 8% 22% 18% 7% 1	2850
	11th to 20th	Day	40% 8% 23% 23% 5%	2850
	21st to end	Day	34% 8% 24% 23% 9% 1	2850
July	1st to 10th	Day	17% 5% 11% 30% 25% 12%	4666
	11th to 20th	Day	14% 4 14% 36% 29% 2	4659
	21st to end	Day	20% 5% 26% 31% 16% 3	4674
August	1st to 10th	Day	14% 5% 18% 44% 17% 2	4267
	11th to 20th	Day	35% 9% 25% 22% 7% 1	4065
	21st to end	Day	36% 6% 20% 29% 9%	4410
September	1st to 10th	Day	30% 8% 21% 25% 14% 3	2280
	11th to 20th	Day	41% 10% 16% 20% 13% 1	2259
	21st to end	Day	44% 9% 16% 22% 9%	2010
October	1st to 10th	Day	48% 8% 18% 22% 4	3180
	11th to 20th	Day	60% 7% 13% 16% 5%	3161
	21st to end	Day	56% 9% 15% 13% 7%	3245
November	1st to 10th	Day	66% 9% 12% 10% 3 1	1568
	11th to 20th	Day	63% 7% 12% 13% 4 1	1600
	21st to end	Day	66% 9% 9% 12% 5%	1600
December	1st to 10th	Day	64% 7% 11% 15% 3	2620
	11th to 20th	Day	72% 9% 10% 7% 2	2688
	21st to end	Day	71% 9% 10% 8% 2	3498
January	1st to 10th	Night	73% 8% 9% 8% 2	6766
	11th to 20th	Night	48% 8% 19% 20% 4	6734
	21st to end	Night	60% 8% 13% 14% 5%	6794
February	1st to 10th	Night	63% 8% 13% 10% 5% 1	2535
	11th to 20th	Night	57% 8% 13% 15% 6% 1	2404
	21st to end	Night	60% 7% 12% 13% 6% 1	2027
March	1st to 10th	Night	54% 11% 14% 16% 6%	3587
	11th to 20th	Night	39% 9% 19% 29% 3 1	3490
	21st to end	Night	61% 11% 13% 14% 2	3750
April	1st to 10th	Night	53% 10% 16% 16% 5%	1900
	11th to 20th	Night	48% 9% 13% 20% 8% 2	1782
	21st to end	Night	52% 8% 13% 18% 9%	1691
May	1st to 10th	Night	35% 6% 15% 30% 12% 1	2540
	11th to 20th	Night	27% 9% 27% 28% 9%	2516
	21st to end	Night	46% 12% 20% 18% 5%	2730
June	1st to 10th	Night	45% 7% 16% 24% 6% 2	1330
	11th to 20th	Night	38% 10% 22% 25% 5%	1330
	21st to end	Night	32% 8% 25% 23% 10% 3	1330
July	1st to 10th	Night	16% 6% 10% 32% 21% 15%	2185
	11th to 20th	Night	14% 3 12% 33% 35% 2	2178
	21st to end	Night	21% 4 15% 34% 23% 3	2637
August	1st to 10th	Night	13% 4 15% 37% 27% 3	2638
	11th to 20th	Night	31% 8% 26% 22% 9% 3	2839
	21st to end	Night	29% 9% 16% 34% 12% 1	3259
September	1st to 10th	Night	22% 7% 20% 30% 17% 5%	1900
	11th to 20th	Night	37% 8% 14% 21% 16% 4	1918
	21st to end	Night	41% 7% 15% 24% 12% 1	2169
October	1st to 10th	Night	41% 6% 20% 25% 8%	3800
	11th to 20th	Night	53% 5% 16% 21% 5%	3777
	21st to end	Night	53% 7% 15% 17% 9%	4315
November	1st to 10th	Night	63% 8% 12% 13% 3 1	2730
	11th to 20th	Night	60% 6% 14% 12% 5% 2	2800
	21st to end	Night	64% 9% 12% 10% 5% 1	2800
December	1st to 10th	Night	57% 8% 14% 17% 4	4560
	11th to 20th	Night	73% 8% 10% 6% 2	5513
	21st to end	Night	65% 9% 12% 10% 2	7458

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% 16% 27% 17% 10% 2	200
	11th to 20th	Day	24% 11% 21% 30% 15% 1	200
	21st to end	Day	28% 8% 21% 22% 17% 4	290
February	1st to 10th	Day	30% 7% 19% 28% 13% 2	386
	11th to 20th	Day	26% 9% 17% 28% 16% 3	365
	21st to end	Day	19% 13% 18% 28% 17% 5%	314
March	1st to 10th	Day	19% 8% 17% 30% 21% 6%	460
	11th to 20th	Day	22% 8% 15% 26% 18% 11%	460
	21st to end	Day	21% 8% 14% 29% 22% 6%	506
April	1st to 10th	Day	15% 12% 18% 25% 20% 9%	460
	11th to 20th	Day	18% 5% 14% 30% 21% 11%	452
	21st to end	Day	18% 7% 18% 25% 23% 10%	460
May	1st to 10th	Day	13% 6% 11% 23% 36% 11%	463
	11th to 20th	Day	13% 3 11% 23% 35% 15%	488
	21st to end	Day	13% 5% 12% 30% 27% 14%	543
June	1st to 10th	Day	15% 4 14% 30% 27% 10%	680
	11th to 20th	Day	10% 6% 16% 36% 26% 7%	680
	21st to end	Day	8% 2 13% 30% 31% 16%	680
July	1st to 10th	Day	7% 1 11% 26% 35% 19%	671
	11th to 20th	Day	5% 1 10% 28% 37% 20%	668
	21st to end	Day	4 2 7% 24% 36% 28%	555
August	1st to 10th	Day	5% 2 6% 19% 34% 34%	487
	11th to 20th	Day	4 1 4 18% 42% 31%	477
	21st to end	Day	9% 2 7% 25% 37% 21%	539
September	1st to 10th	Day	11% 1 6% 23% 42% 17%	490
	11th to 20th	Day	14% 2 8% 22% 37% 18%	490
	21st to end	Day	16% 3 12% 26% 30% 13%	490
October	1st to 10th	Day	19% 4 13% 23% 26% 14%	490
	11th to 20th	Day	26% 6% 12% 23% 23% 10%	490
	21st to end	Day	24% 9% 20% 27% 15% 6%	435
November	1st to 10th	Day	31% 5% 21% 26% 17% 2	200
	11th to 20th	Day	25% 11% 16% 25% 18% 7%	200
	21st to end	Day	26% 10% 23% 25% 11% 7%	200
December	1st to 10th	Day	27% 9% 21% 19% 21% 4	200
	11th to 20th	Day	37% 11% 21% 20% 12%	200
	21st to end	Day	37% 11% 21% 23% 7%	220
January	1st to 10th	Night	31% 10% 24% 21% 12% 2	900
	11th to 20th	Night	29% 7% 17% 25% 20% 2	890
	21st to end	Night	28% 6% 16% 25% 21% 4	880
February	1st to 10th	Night	28% 9% 19% 26% 14% 3	780
	11th to 20th	Night	25% 7% 20% 26% 19% 3	744
	21st to end	Night	27% 11% 20% 21% 15% 5%	628
March	1st to 10th	Night	23% 8% 17% 26% 20% 5%	760
	11th to 20th	Night	22% 8% 19% 24% 21% 6%	760
	21st to end	Night	23% 8% 18% 26% 20% 4	836
April	1st to 10th	Night	21% 8% 19% 25% 22% 5%	760
	11th to 20th	Night	18% 5% 23% 28% 19% 7%	654
	21st to end	Night	20% 5% 23% 32% 16% 4	551
May	1st to 10th	Night	12% 4 22% 31% 26% 5%	380
	11th to 20th	Night	11% 5% 17% 29% 30% 9%	374
	21st to end	Night	12% 7% 18% 31% 25% 7%	411
June	1st to 10th	Night	16% 5% 20% 30% 26% 3	380
	11th to 20th	Night	14% 4 20% 39% 19% 4	380
	21st to end	Night	9% 3 19% 33% 26% 11%	380
July	1st to 10th	Night	10% 1 15% 34% 35% 6%	370
	11th to 20th	Night	6% 2 17% 36% 33% 7%	368
	21st to end	Night	5% 3 13% 33% 36% 10%	416
August	1st to 10th	Night	5% 1 10% 29% 44% 11%	443
	11th to 20th	Night	5% 1 5% 24% 49% 15%	564
	21st to end	Night	9% 1 12% 31% 38% 9%	688
September	1st to 10th	Night	8% 2 8% 31% 35% 16%	760
	11th to 20th	Night	14% 3 8% 24% 31% 19%	760
	21st to end	Night	16% 2 12% 28% 31% 11%	760
October	1st to 10th	Night	18% 3 11% 25% 28% 15%	760
	11th to 20th	Night	24% 4 12% 25% 24% 11%	760
	21st to end	Night	26% 5% 17% 27% 19% 5%	836
November	1st to 10th	Night	31% 7% 17% 25% 18% 2	780
	11th to 20th	Night	28% 9% 20% 24% 16% 3	800
	21st to end	Night	27% 8% 21% 23% 15% 6%	800
December	1st to 10th	Night	27% 7% 18% 25% 21% 3	800
	11th to 20th	Night	31% 9% 24% 24% 11% 2	885
	21st to end	Night	31% 10% 25% 24% 9% 1	990

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