McCloud Nature Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the McCloud Nature Park 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	14% 9% 3 8% 5% 5% 5% 4 6% 7% 36%	131682
	Night	14% 10% 4 8% 5% 4 4 3 5% 6% 37%	131678
Transparency	Day	46% 5% 11% 24% 13% 2	135276
	Night	46% 4 10% 23% 15% 2	136160
Seeing	Day	16% 11% 27% 24% 16% 6%	17689
	Night	17% 10% 29% 30% 13% 1	27572

By Month

Percentage Cloud Cover SE (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% 13% 7% 13% 6% 4 4 3 5% 7% 24%	4691
	11th to 20th	Day	9% 10% 7% 15% 8% 8% 7% 5% 5% 5% 22%	4710
	21st to end	Day	17% 15% 6% 14% 6% 5% 4 4 4 4 21%	5350
February	1st to 10th	Day	16% 13% 6% 9% 6% 6% 4 3 5% 5% 27%	2100
	11th to 20th	Day	15% 11% 4 11% 6% 5% 5% 4 5% 6% 29%	2048
	21st to end	Day	16% 13% 5% 10% 4 4 3 3 5% 6% 32%	1730
March	1st to 10th	Day	20% 15% 4 7% 4 4 3 2 3 4 34%	4580
	11th to 20th	Day	10% 9% 3 6% 4 4 4 3 5% 8% 42%	4851
	21st to end	Day	17% 11% 4 8% 5% 4 4 3 5% 7% 31%	5929
April	1st to 10th	Day	16% 11% 4 7% 4 4 4 3 5% 8% 34%	2520
	11th to 20th	Day	16% 10% 2 7% 4 5% 5% 4 5% 7% 36%	2494
	21st to end	Day	19% 8% 3 7% 5% 5% 4 3 6% 7% 35%	2667
May	1st to 10th	Day	20% 9% 3 7% 5% 5% 5% 4 6% 8% 29%	5992
	11th to 20th	Day	18% 8% 3 6% 4 4 5% 3 5% 7% 36%	5991
	21st to end	Day	13% 7% 2 8% 5% 5% 5% 5% 7% 9% 34%	6848
June	1st to 10th	Day	11% 6% 2 5% 5% 5% 5% 4 6% 8% 43%	2801
	11th to 20th	Day	9% 6% 2 5% 4 5% 5% 6% 6% 9% 44%	2800
	21st to end	Day	9% 6% 3 7% 4 5% 4 4 6% 10% 42%	2800
July	1st to 10th	Day	11% 5% 2 5% 4 4 5% 4 6% 11% 43%	6360
	11th to 20th	Day	9% 6% 3 6% 5% 5% 6% 5% 8% 11% 36%	6360
	21st to end	Day	12% 6% 2 7% 5% 5% 6% 5% 7% 9% 37%	6834
August	1st to 10th	Day	8% 5% 2 5% 3 4 5% 4 6% 9% 50%	4234
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 4 7% 11% 41%	3920
	21st to end	Day	6% 4 2 5% 3 4 4 3 6% 9% 53%	4312
September	1st to 10th	Day	11% 6% 2 6% 4 4 5% 3 5% 8% 47%	2393
	11th to 20th	Day	9% 5% 2 4 4 4 5% 5% 6% 7% 51%	2200
	21st to end	Day	13% 6% 2 5% 4 4 4 3 5% 6% 48%	2200
October	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 5% 7% 49%	2200
	11th to 20th	Day	14% 6% 3 6% 5% 4 4 3 5% 7% 43%	2030
	21st to end	Day	17% 9% 3 7% 5% 4 4 4 4 6% 36%	1980
November	1st to 10th	Day	10% 6% 3 5% 4 3 4 3 6% 5% 51%	1852
	11th to 20th	Day	17% 11% 3 7% 5% 4 4 3 5% 6% 37%	1890
	21st to end	Day	18% 11% 3 9% 5% 3 3 3 4 6% 33%	1890
December	1st to 10th	Day	13% 11% 4 8% 5% 4 3 3 4 5% 41%	2967
	11th to 20th	Day	16% 15% 6% 11% 5% 5% 5% 4 5% 6% 23%	3088
	21st to end	Day	27% 17% 7% 10% 5% 3 4 3 5% 5% 14%	4070
January	1st to 10th	Night	15% 14% 7% 13% 6% 4 5% 4 4 5% 25%	8232
	11th to 20th	Night	10% 16% 6% 13% 7% 6% 6% 3 5% 4 24%	8280
	21st to end	Night	17% 11% 5% 9% 6% 5% 4 4 5% 6% 29%	8841
February	1st to 10th	Night	18% 11% 4 10% 4 5% 4 3 5% 5% 30%	2520
	11th to 20th	Night	15% 11% 5% 9% 5% 4 4 3 5% 6% 32%	2458
	21st to end	Night	17% 12% 4 9% 5% 4 4 3 5% 5% 32%	2076
March	1st to 10th	Night	19% 15% 4 6% 3 3 3 2 4 5% 36%	5493
	11th to 20th	Night	14% 6% 3 6% 4 4 4 3 5% 7% 45%	5328
	21st to end	Night	18% 8% 4 8% 5% 4 5% 3 5% 6% 34%	5271
April	1st to 10th	Night	15% 9% 3 6% 4 5% 4 4 5% 7% 38%	2100
	11th to 20th	Night	16% 9% 2 6% 4 4 4 4 5% 7% 40%	2075
	21st to end	Night	16% 8% 3 6% 5% 5% 4 3 6% 6% 37%	1952
May	1st to 10th	Night	19% 11% 3 9% 4 5% 5% 4 4 7% 30%	4123
	11th to 20th	Night	16% 7% 3 6% 4 4 3 4 6% 8% 38%	4122
	21st to end	Night	14% 7% 3 7% 5% 5% 5% 4 5% 8% 37%	4256
June	1st to 10th	Night	10% 6% 3 6% 4 3 4 3 5% 8% 49%	1600
	11th to 20th	Night	10% 5% 2 6% 5% 4 3 3 6% 8% 48%	1600
	21st to end	Night	6% 5% 2 6% 5% 5% 5% 5% 7% 10% 46%	1600
July	1st to 10th	Night	9% 4 2 5% 4 4 4 4 6% 10% 47%	3618
	11th to 20th	Night	8% 6% 2 5% 3 4 5% 4 7% 9% 46%	3617
	21st to end	Night	9% 7% 3 7% 5% 5% 5% 4 7% 10% 39%	4032
August	1st to 10th	Night	9% 5% 2 5% 3 4 4 3 6% 8% 53%	2915
	11th to 20th	Night	7% 5% 2 6% 5% 5% 5% 4 5% 9% 48%	3126
	21st to end	Night	6% 3 2 5% 3 3 4 3 5% 8% 58%	3586
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 5% 7% 50%	2000
	11th to 20th	Night	6% 4 1 5% 4 4 4 3 5% 8% 57%	2185
	21st to end	Night	12% 6% 2 5% 4 4 3 3 6% 6% 49%	2200
October	1st to 10th	Night	8% 4 2 5% 4 4 4 3 5% 7% 55%	2200
	11th to 20th	Night	16% 6% 2 5% 3 3 3 3 4 6% 48%	2365
	21st to end	Night	17% 8% 2 6% 4 4 4 3 5% 7% 40%	2860
November	1st to 10th	Night	11% 7% 3 5% 4 3 4 3 5% 6% 50%	2666
	11th to 20th	Night	13% 10% 3 7% 4 4 4 4 5% 6% 40%	2730
	21st to end	Night	20% 12% 4 8% 4 4 4 2 5% 5% 33%	2730
December	1st to 10th	Night	14% 10% 4 8% 5% 3 3 3 5% 5% 39%	4432
	11th to 20th	Night	17% 12% 5% 11% 4 4 4 3 5% 5% 28%	5339
	21st to end	Night	27% 18% 7% 9% 5% 4 4 3 4 4 16%	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	60% 3 12% 19% 6% 1	4692
	11th to 20th	Day	64% 3 8% 12% 10% 2	4710
	21st to end	Day	67% 3 7% 16% 5% 2	5350
February	1st to 10th	Day	59% 4 9% 18% 9% 1	2100
	11th to 20th	Day	55% 4 10% 21% 9% 1	2058
	21st to end	Day	53% 3 10% 22% 9% 2	1730
March	1st to 10th	Day	56% 3 6% 20% 13% 3	4580
	11th to 20th	Day	40% 4 10% 34% 11% 1	4851
	21st to end	Day	53% 3 13% 21% 8% 1	5931
April	1st to 10th	Day	49% 5% 11% 21% 14% 1	2520
	11th to 20th	Day	47% 4 11% 24% 11% 3	2494
	21st to end	Day	49% 4 11% 23% 10% 2	2667
May	1st to 10th	Day	53% 5% 12% 21% 9% 1	6027
	11th to 20th	Day	48% 5% 11% 25% 10% 1	5995
	21st to end	Day	43% 7% 12% 23% 14% 2	6862
June	1st to 10th	Day	38% 5% 13% 26% 15% 3	2801
	11th to 20th	Day	35% 6% 11% 25% 20% 3	2800
	21st to end	Day	36% 7% 16% 20% 17% 4	2800
July	1st to 10th	Day	36% 5% 11% 29% 18% 2	6291
	11th to 20th	Day	38% 9% 16% 24% 13% 1	6285
	21st to end	Day	41% 9% 13% 23% 12% 2	6640
August	1st to 10th	Day	29% 7% 15% 32% 15% 1	4221
	11th to 20th	Day	34% 7% 13% 30% 15% 1	3958
	21st to end	Day	27% 5% 15% 32% 17% 4	4311
September	1st to 10th	Day	35% 5% 11% 27% 18% 4	2393
	11th to 20th	Day	31% 6% 10% 27% 23% 3	2200
	21st to end	Day	36% 5% 10% 24% 23% 2	2200
October	1st to 10th	Day	22% 3 8% 31% 33% 2	3590
	11th to 20th	Day	31% 5% 9% 27% 27% 2	3285
	21st to end	Day	42% 3 9% 23% 23% 1	3180
November	1st to 10th	Day	36% 3 12% 27% 18% 4	1852
	11th to 20th	Day	49% 3 8% 22% 14% 4	1890
	21st to end	Day	53% 3 8% 22% 12% 1	1890
December	1st to 10th	Day	47% 3 9% 28% 13%	2967
	11th to 20th	Day	61% 4 8% 19% 6%	3085
	21st to end	Day	73% 3 9% 10% 5%	4070
January	1st to 10th	Night	61% 4 10% 18% 6%	8233
	11th to 20th	Night	64% 3 7% 13% 10% 3	8280
	21st to end	Night	56% 3 10% 21% 9% 1	8841
February	1st to 10th	Night	57% 3 11% 19% 9% 1	2520
	11th to 20th	Night	53% 3 10% 20% 13% 2	2459
	21st to end	Night	54% 4 11% 20% 11% 2	2076
March	1st to 10th	Night	52% 2 6% 24% 12% 4	5493
	11th to 20th	Night	40% 4 9% 27% 18% 2	5328
	21st to end	Night	50% 4 10% 27% 8% 1	5271
April	1st to 10th	Night	46% 4 12% 23% 14% 2	2100
	11th to 20th	Night	44% 4 9% 22% 16% 4	2075
	21st to end	Night	46% 4 10% 24% 13% 3	1952
May	1st to 10th	Night	55% 5% 10% 18% 10% 2	4150
	11th to 20th	Night	44% 5% 11% 26% 13%	4123
	21st to end	Night	43% 7% 13% 21% 13% 3	4264
June	1st to 10th	Night	35% 4 10% 27% 21% 4	1600
	11th to 20th	Night	35% 5% 12% 24% 20% 5%	1600
	21st to end	Night	32% 6% 15% 24% 18% 4	1600
July	1st to 10th	Night	32% 7% 10% 29% 19% 3	3580
	11th to 20th	Night	32% 7% 15% 29% 16% 1	3572
	21st to end	Night	38% 7% 15% 24% 13% 2	3916
August	1st to 10th	Night	29% 7% 15% 34% 14% 1	2904
	11th to 20th	Night	32% 6% 13% 30% 17% 1	3154
	21st to end	Night	25% 6% 12% 32% 21% 4	3586
September	1st to 10th	Night	33% 5% 12% 25% 20% 6%	2000
	11th to 20th	Night	27% 4 9% 27% 29% 4	2185
	21st to end	Night	36% 4 9% 23% 24% 4	2200
October	1st to 10th	Night	20% 3 6% 27% 41% 2	3590
	11th to 20th	Night	28% 3 8% 25% 34% 2	3849
	21st to end	Night	36% 3 7% 24% 24% 5%	4610
November	1st to 10th	Night	35% 4 9% 27% 21% 4	2666
	11th to 20th	Night	44% 3 9% 25% 16% 3	2730
	21st to end	Night	55% 3 8% 22% 11% 1	2730
December	1st to 10th	Night	47% 3 11% 26% 12%	4432
	11th to 20th	Night	58% 3 10% 18% 11% 1	5341
	21st to end	Night	72% 3 8% 11% 5%	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	23% 15% 35% 21% 6% 1	330
	11th to 20th	Day	19% 23% 37% 16% 3 1	330
	21st to end	Day	23% 19% 32% 22% 4	363
February	1st to 10th	Day	24% 15% 37% 21% 5%	330
	11th to 20th	Day	24% 20% 35% 14% 6% 1	330
	21st to end	Day	24% 17% 38% 18% 2	273
March	1st to 10th	Day	22% 23% 37% 14% 3	330
	11th to 20th	Day	24% 21% 36% 14% 6%	431
	21st to end	Day	26% 17% 33% 18% 6%	594
April	1st to 10th	Day	20% 18% 32% 21% 8% 1	540
	11th to 20th	Day	19% 21% 27% 20% 11% 2	532
	21st to end	Day	21% 14% 34% 19% 9% 2	540
May	1st to 10th	Day	19% 14% 31% 24% 9% 2	543
	11th to 20th	Day	18% 10% 29% 26% 12% 5%	567
	21st to end	Day	13% 6% 29% 25% 18% 9%	733
June	1st to 10th	Day	12% 6% 26% 31% 19% 6%	731
	11th to 20th	Day	10% 6% 26% 32% 18% 6%	730
	21st to end	Day	11% 6% 29% 27% 21% 6%	730
July	1st to 10th	Day	10% 3 17% 26% 25% 18%	721
	11th to 20th	Day	8% 3 19% 34% 23% 14%	718
	21st to end	Day	10% 3 15% 32% 31% 10%	754
August	1st to 10th	Day	8% 3 14% 27% 30% 17%	526
	11th to 20th	Day	13% 2 16% 29% 29% 10%	519
	21st to end	Day	7% 2 13% 30% 32% 15%	583
September	1st to 10th	Day	10% 4 15% 29% 31% 10%	530
	11th to 20th	Day	8% 3 14% 27% 31% 17%	530
	21st to end	Day	14% 9% 21% 23% 22% 11%	530
October	1st to 10th	Day	10% 5% 25% 31% 20% 8%	530
	11th to 20th	Day	13% 12% 33% 26% 14% 3	415
	21st to end	Day	25% 17% 34% 21% 3	363
November	1st to 10th	Day	13% 14% 33% 25% 12% 3	330
	11th to 20th	Day	24% 17% 29% 18% 10% 1	330
	21st to end	Day	25% 12% 38% 22% 4	330
December	1st to 10th	Day	15% 21% 38% 20% 4 1	330
	11th to 20th	Day	21% 16% 40% 16% 6% 1	330
	21st to end	Day	29% 16% 34% 18% 4	363
January	1st to 10th	Night	22% 15% 35% 24% 4	1050
	11th to 20th	Night	22% 16% 39% 19% 4	1050
	21st to end	Night	20% 15% 38% 24% 3	1121
February	1st to 10th	Night	23% 12% 38% 25% 2	840
	11th to 20th	Night	20% 16% 38% 24% 2	823
	21st to end	Night	23% 13% 39% 23% 2	692
March	1st to 10th	Night	23% 15% 34% 24% 4	840
	11th to 20th	Night	20% 14% 38% 23% 5%	840
	21st to end	Night	24% 12% 34% 26% 4 1	788
April	1st to 10th	Night	17% 13% 36% 27% 6%	630
	11th to 20th	Night	18% 12% 31% 29% 9%	623
	21st to end	Night	20% 11% 35% 26% 7% 1	630
May	1st to 10th	Night	19% 7% 37% 28% 9%	630
	11th to 20th	Night	17% 7% 26% 33% 15% 2	621
	21st to end	Night	10% 5% 25% 37% 21% 2	683
June	1st to 10th	Night	12% 4 23% 42% 18% 1	600
	11th to 20th	Night	10% 5% 20% 45% 19% 1	600
	21st to end	Night	7% 3 21% 42% 26% 1	600
July	1st to 10th	Night	10% 1 10% 40% 32% 6%	585
	11th to 20th	Night	6% 3 16% 38% 33% 4	582
	21st to end	Night	7% 2 12% 44% 32% 3	657
August	1st to 10th	Night	8% 2 9% 44% 33% 4	597
	11th to 20th	Night	7% 2 11% 42% 33% 4	594
	21st to end	Night	8% 2 13% 33% 39% 5%	660
September	1st to 10th	Night	13% 3 13% 35% 33% 4	600
	11th to 20th	Night	7% 3 15% 36% 34% 4	785
	21st to end	Night	13% 7% 19% 34% 24% 3	800
October	1st to 10th	Night	9% 6% 23% 37% 22% 4	800
	11th to 20th	Night	19% 10% 27% 30% 14% 1	800
	21st to end	Night	21% 11% 33% 27% 7%	880
November	1st to 10th	Night	15% 8% 37% 30% 9% 1	820
	11th to 20th	Night	17% 16% 34% 26% 7% 1	840
	21st to end	Night	25% 13% 28% 28% 6%	840
December	1st to 10th	Night	22% 12% 39% 22% 4	866
	11th to 20th	Night	24% 10% 36% 23% 6%	1050
	21st to end	Night	30% 15% 31% 21% 3	1155

Page generated at 2026-05-29 00:53:31. Version ac07

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