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 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 4 6% 7% 37%	108264
	Night	15% 10% 4 8% 5% 4 4 3 5% 6% 37%	110140
Transparency	Day	45% 5% 11% 24% 14% 2	111903
	Night	46% 4 10% 22% 15% 2	114643
Seeing	Day	16% 10% 27% 25% 16% 6%	15887
	Night	17% 9% 29% 30% 14% 1	25840

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% 8% 14% 7% 5% 4 3 5% 5% 23%	3617
	11th to 20th	Day	11% 11% 8% 15% 7% 8% 6% 5% 5% 4 20%	3620
	21st to end	Day	20% 17% 6% 13% 4 4 3 3 3 4 24%	4122
February	1st to 10th	Day	17% 13% 5% 10% 6% 6% 4 3 5% 5% 26%	1950
	11th to 20th	Day	15% 10% 4 10% 6% 5% 5% 4 6% 6% 30%	1848
	21st to end	Day	17% 13% 5% 9% 5% 4 3 3 5% 6% 31%	1570
March	1st to 10th	Day	21% 18% 3 6% 4 4 3 2 3 5% 30%	3120
	11th to 20th	Day	12% 8% 3 6% 4 4 4 3 5% 7% 43%	3316
	21st to end	Day	16% 9% 5% 8% 5% 5% 4 3 6% 7% 30%	4055
April	1st to 10th	Day	15% 11% 4 7% 4 4 4 3 5% 8% 35%	2280
	11th to 20th	Day	16% 9% 2 7% 5% 5% 4 3 5% 7% 37%	2254
	21st to end	Day	20% 8% 3 7% 5% 5% 4 3 6% 7% 34%	2413
May	1st to 10th	Day	19% 9% 3 7% 5% 4 5% 4 6% 8% 29%	4082
	11th to 20th	Day	19% 7% 2 5% 4 4 4 3 5% 8% 37%	4081
	21st to end	Day	10% 6% 2 7% 5% 5% 5% 5% 7% 9% 41%	4658
June	1st to 10th	Day	11% 6% 2 5% 5% 5% 5% 4 7% 8% 43%	2660
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 6% 6% 8% 46%	2660
	21st to end	Day	10% 6% 3 7% 4 5% 4 4 6% 10% 41%	2660
July	1st to 10th	Day	13% 6% 3 6% 4 4 5% 4 6% 10% 38%	4440
	11th to 20th	Day	7% 4 2 5% 4 4 5% 4 8% 11% 45%	4440
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 5% 7% 10% 37%	4751
August	1st to 10th	Day	8% 5% 2 5% 3 4 5% 4 6% 9% 49%	4104
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 4 7% 11% 42%	3798
	21st to end	Day	7% 4 2 5% 3 4 4 3 6% 9% 53%	4180
September	1st to 10th	Day	11% 6% 2 6% 4 4 5% 3 5% 8% 46%	2274
	11th to 20th	Day	10% 5% 2 4 4 4 5% 5% 6% 7% 49%	2090
	21st to end	Day	13% 6% 2 5% 4 4 4 3 5% 6% 48%	2090
October	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 5% 7% 49%	2090
	11th to 20th	Day	14% 6% 3 6% 5% 4 4 4 6% 7% 42%	1929
	21st to end	Day	18% 9% 3 7% 5% 4 5% 4 4 6% 35%	1881
November	1st to 10th	Day	10% 6% 3 5% 4 3 4 3 6% 5% 51%	1762
	11th to 20th	Day	16% 12% 3 7% 5% 4 4 3 5% 6% 37%	1800
	21st to end	Day	18% 12% 3 9% 5% 3 3 4 5% 6% 33%	1800
December	1st to 10th	Day	13% 11% 3 8% 5% 4 3 3 4 5% 41%	2879
	11th to 20th	Day	16% 15% 6% 11% 5% 5% 5% 4 5% 6% 23%	3008
	21st to end	Day	27% 18% 7% 10% 5% 3 4 3 5% 5% 14%	3982
January	1st to 10th	Night	15% 14% 8% 14% 6% 4 5% 3 4 5% 22%	6348
	11th to 20th	Night	12% 19% 6% 13% 7% 6% 6% 4 4 3 20%	6360
	21st to end	Night	20% 12% 6% 9% 6% 4 3 3 4 5% 29%	6835
February	1st to 10th	Night	19% 11% 4 10% 5% 5% 3 3 5% 5% 29%	2341
	11th to 20th	Night	14% 11% 5% 9% 5% 4 4 3 5% 6% 32%	2218
	21st to end	Night	18% 12% 4 9% 5% 4 4 3 5% 5% 31%	1884
March	1st to 10th	Night	20% 16% 3 7% 4 3 3 3 4 5% 33%	3733
	11th to 20th	Night	14% 6% 2 6% 4 4 4 3 4 7% 47%	3643
	21st to end	Night	18% 8% 4 7% 4 3 5% 3 5% 6% 37%	3604
April	1st to 10th	Night	14% 9% 3 6% 4 5% 4 3 5% 7% 39%	1900
	11th to 20th	Night	16% 9% 2 6% 4 4 4 4 5% 7% 40%	1875
	21st to end	Night	17% 8% 3 7% 5% 5% 4 3 6% 6% 37%	1766
May	1st to 10th	Night	17% 11% 3 8% 5% 4 5% 4 5% 8% 29%	2813
	11th to 20th	Night	19% 6% 2 5% 4 4 3 4 6% 7% 40%	2812
	21st to end	Night	10% 5% 2 6% 4 4 5% 4 6% 9% 44%	2899
June	1st to 10th	Night	9% 6% 3 6% 4 3 4 3 5% 8% 49%	1520
	11th to 20th	Night	9% 5% 2 6% 5% 4 3 3 6% 8% 49%	1520
	21st to end	Night	7% 5% 2 6% 5% 5% 5% 5% 7% 10% 45%	1520
July	1st to 10th	Night	11% 4 2 5% 4 3 4 4 6% 10% 48%	2530
	11th to 20th	Night	6% 4 1 4 3 4 4 4 7% 9% 56%	2530
	21st to end	Night	9% 7% 2 7% 5% 4 4 4 6% 11% 41%	2809
August	1st to 10th	Night	9% 5% 2 5% 3 4 4 3 6% 8% 53%	2825
	11th to 20th	Night	7% 5% 2 6% 5% 5% 5% 4 5% 9% 48%	3028
	21st to end	Night	6% 3 2 5% 4 3 4 3 5% 8% 57%	3476
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 5% 7% 49%	1900
	11th to 20th	Night	6% 4 1 5% 4 4 4 4 5% 8% 55%	2076
	21st to end	Night	12% 6% 2 5% 4 4 4 3 6% 6% 49%	2090
October	1st to 10th	Night	8% 4 2 5% 4 4 4 3 5% 7% 55%	2090
	11th to 20th	Night	16% 6% 2 5% 3 3 3 3 4 6% 48%	2246
	21st to end	Night	17% 8% 2 6% 4 4 4 3 5% 7% 40%	2717
November	1st to 10th	Night	11% 7% 3 5% 4 3 4 3 5% 6% 50%	2536
	11th to 20th	Night	14% 10% 3 7% 4 4 4 4 5% 6% 40%	2600
	21st to end	Night	20% 12% 4 8% 4 4 4 2 5% 5% 33%	2600
December	1st to 10th	Night	14% 9% 4 8% 5% 3 3 3 5% 5% 40%	4301
	11th to 20th	Night	18% 12% 5% 11% 4 4 4 3 5% 5% 28%	5199
	21st to end	Night	27% 18% 7% 9% 5% 4 4 3 4 4 16%	6996

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	64% 2 7% 20% 6% 1	3618
	11th to 20th	Day	67% 4 9% 10% 9% 2	3620
	21st to end	Day	66% 2 8% 16% 6% 2	4122
February	1st to 10th	Day	60% 3 9% 17% 9% 2	1950
	11th to 20th	Day	54% 4 11% 22% 9% 1	1858
	21st to end	Day	55% 3 9% 22% 8% 2	1570
March	1st to 10th	Day	60% 3 6% 19% 11% 2	3120
	11th to 20th	Day	40% 4 11% 30% 13% 1	3316
	21st to end	Day	53% 3 14% 24% 5% 1	4055
April	1st to 10th	Day	48% 4 12% 21% 14% 1	2280
	11th to 20th	Day	47% 4 11% 24% 11% 3	2254
	21st to end	Day	50% 3 12% 21% 11% 3	2413
May	1st to 10th	Day	52% 5% 14% 24% 6%	4120
	11th to 20th	Day	46% 5% 13% 27% 9%	4085
	21st to end	Day	38% 6% 11% 23% 19% 2	4671
June	1st to 10th	Day	38% 6% 13% 26% 15% 3	2660
	11th to 20th	Day	33% 6% 11% 25% 21% 3	2660
	21st to end	Day	37% 7% 16% 20% 17% 4	2660
July	1st to 10th	Day	41% 6% 11% 25% 14% 2	4371
	11th to 20th	Day	29% 7% 15% 29% 17% 1	4365
	21st to end	Day	39% 9% 15% 20% 15% 3	4602
August	1st to 10th	Day	30% 7% 16% 31% 15% 1	4091
	11th to 20th	Day	34% 6% 13% 30% 15% 1	3836
	21st to end	Day	27% 5% 15% 31% 17% 4	4179
September	1st to 10th	Day	36% 5% 10% 26% 18% 4	2274
	11th to 20th	Day	32% 6% 11% 26% 23% 3	2090
	21st to end	Day	37% 4 10% 25% 22% 2	2090
October	1st to 10th	Day	22% 3 9% 31% 32% 2	3480
	11th to 20th	Day	31% 5% 9% 27% 27% 2	3184
	21st to end	Day	42% 3 9% 23% 22% 1	3081
November	1st to 10th	Day	35% 3 13% 26% 18% 4	1762
	11th to 20th	Day	49% 3 8% 22% 14% 4	1800
	21st to end	Day	53% 4 8% 22% 12% 2	1800
December	1st to 10th	Day	47% 3 9% 29% 13%	2879
	11th to 20th	Day	61% 4 8% 19% 6%	3005
	21st to end	Day	73% 3 9% 11% 5%	3982
January	1st to 10th	Night	65% 3 8% 17% 7%	6348
	11th to 20th	Night	69% 2 7% 11% 8% 3	6360
	21st to end	Night	60% 2 8% 19% 9% 1	6835
February	1st to 10th	Night	58% 3 11% 18% 9% 1	2341
	11th to 20th	Night	52% 3 10% 19% 13% 2	2219
	21st to end	Night	55% 4 11% 18% 11% 2	1884
March	1st to 10th	Night	55% 3 8% 23% 11% 2	3733
	11th to 20th	Night	39% 4 9% 25% 21% 2	3643
	21st to end	Night	48% 3 12% 28% 8% 1	3604
April	1st to 10th	Night	45% 3 12% 23% 14% 2	1900
	11th to 20th	Night	44% 4 9% 22% 16% 5%	1875
	21st to end	Night	47% 4 10% 21% 13% 4	1766
May	1st to 10th	Night	54% 5% 11% 21% 8% 1	2840
	11th to 20th	Night	44% 5% 12% 28% 10%	2813
	21st to end	Night	35% 6% 13% 24% 18% 4	2907
June	1st to 10th	Night	34% 4 11% 27% 21% 3	1520
	11th to 20th	Night	33% 5% 12% 24% 21% 5%	1520
	21st to end	Night	33% 7% 15% 24% 18% 4	1520
July	1st to 10th	Night	33% 6% 11% 28% 18% 4	2490
	11th to 20th	Night	23% 6% 13% 33% 23% 2	2482
	21st to end	Night	38% 7% 16% 21% 16% 3	2720
August	1st to 10th	Night	29% 7% 15% 34% 14% 1	2814
	11th to 20th	Night	33% 6% 13% 30% 18% 1	3056
	21st to end	Night	26% 6% 12% 32% 21% 4	3476
September	1st to 10th	Night	33% 5% 12% 24% 19% 6%	1900
	11th to 20th	Night	27% 4 9% 27% 27% 5%	2076
	21st to end	Night	36% 4 9% 24% 23% 4	2090
October	1st to 10th	Night	20% 3 7% 27% 41% 2	3480
	11th to 20th	Night	28% 3 8% 25% 34% 2	3730
	21st to end	Night	35% 3 8% 25% 24% 5%	4467
November	1st to 10th	Night	36% 4 9% 27% 21% 4	2536
	11th to 20th	Night	44% 3 9% 24% 17% 4	2600
	21st to end	Night	54% 3 8% 22% 11% 1	2600
December	1st to 10th	Night	47% 3 11% 26% 12%	4301
	11th to 20th	Night	58% 3 10% 17% 11% 1	5201
	21st to end	Night	72% 3 8% 11% 5%	6996

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	300
	11th to 20th	Day	20% 21% 37% 18% 3 1	300
	21st to end	Day	24% 17% 32% 22% 5%	330
February	1st to 10th	Day	25% 15% 36% 19% 4	285
	11th to 20th	Day	24% 20% 33% 16% 7% 1	270
	21st to end	Day	27% 15% 38% 18% 3	225
March	1st to 10th	Day	23% 24% 33% 16% 4	270
	11th to 20th	Day	24% 20% 36% 14% 6% 1	361
	21st to end	Day	28% 15% 32% 18% 7%	506
April	1st to 10th	Day	18% 18% 31% 22% 9% 1	460
	11th to 20th	Day	20% 18% 27% 20% 12% 2	452
	21st to end	Day	23% 15% 33% 18% 8% 2	460
May	1st to 10th	Day	19% 14% 29% 26% 10% 3	463
	11th to 20th	Day	18% 9% 28% 27% 13% 6%	487
	21st to end	Day	11% 4 28% 27% 20% 10%	633
June	1st to 10th	Day	11% 6% 26% 30% 20% 6%	680
	11th to 20th	Day	10% 6% 26% 33% 19% 7%	680
	21st to end	Day	11% 6% 30% 26% 20% 6%	680
July	1st to 10th	Day	11% 4 17% 26% 24% 19%	671
	11th to 20th	Day	7% 3 19% 34% 23% 14%	668
	21st to end	Day	10% 3 15% 33% 30% 10%	701
August	1st to 10th	Day	8% 3 14% 28% 29% 18%	486
	11th to 20th	Day	14% 2 17% 30% 27% 10%	479
	21st to end	Day	7% 2 12% 29% 33% 16%	539
September	1st to 10th	Day	11% 4 15% 30% 31% 10%	490
	11th to 20th	Day	8% 4 14% 27% 31% 16%	490
	21st to end	Day	14% 10% 21% 23% 21% 11%	490
October	1st to 10th	Day	11% 5% 28% 30% 19% 7%	490
	11th to 20th	Day	13% 13% 35% 25% 12% 3	381
	21st to end	Day	26% 15% 34% 21% 3	330
November	1st to 10th	Day	13% 13% 33% 25% 13% 3	300
	11th to 20th	Day	23% 16% 31% 18% 10% 1	300
	21st to end	Day	24% 13% 38% 22% 4	300
December	1st to 10th	Day	16% 22% 37% 19% 4 1	300
	11th to 20th	Day	22% 15% 40% 16% 6% 1	300
	21st to end	Day	30% 16% 32% 18% 4	330
January	1st to 10th	Night	22% 15% 34% 25% 4	1000
	11th to 20th	Night	23% 15% 38% 20% 4	1000
	21st to end	Night	21% 14% 38% 25% 3	1068
February	1st to 10th	Night	24% 11% 38% 24% 2	781
	11th to 20th	Night	19% 15% 39% 24% 2	743
	21st to end	Night	24% 13% 38% 23% 2	628
March	1st to 10th	Night	22% 14% 34% 25% 5%	760
	11th to 20th	Night	20% 13% 38% 23% 6% 1	760
	21st to end	Night	25% 10% 34% 26% 5% 1	713
April	1st to 10th	Night	17% 13% 35% 28% 7%	570
	11th to 20th	Night	19% 11% 30% 30% 9%	563
	21st to end	Night	22% 11% 35% 24% 7% 1	570
May	1st to 10th	Night	19% 6% 37% 28% 9%	570
	11th to 20th	Night	18% 6% 24% 33% 17% 2	561
	21st to end	Night	10% 4 24% 38% 23% 2	617
June	1st to 10th	Night	11% 4 23% 42% 19% 1	570
	11th to 20th	Night	9% 4 21% 45% 20% 1	570
	21st to end	Night	7% 3 22% 42% 26% 1	570
July	1st to 10th	Night	10% 1 11% 40% 32% 6%	555
	11th to 20th	Night	6% 3 16% 38% 33% 4	552
	21st to end	Night	7% 2 12% 45% 31% 3	624
August	1st to 10th	Night	8% 2 9% 44% 33% 4	567
	11th to 20th	Night	8% 1 12% 42% 33% 4	564
	21st to end	Night	8% 2 13% 31% 41% 6%	627
September	1st to 10th	Night	13% 3 12% 35% 33% 4	570
	11th to 20th	Night	8% 3 15% 36% 34% 4	746
	21st to end	Night	13% 7% 20% 34% 24% 3	760
October	1st to 10th	Night	9% 6% 24% 36% 21% 4	760
	11th to 20th	Night	19% 10% 28% 28% 14% 1	760
	21st to end	Night	21% 10% 33% 28% 7%	836
November	1st to 10th	Night	15% 8% 37% 29% 10% 1	780
	11th to 20th	Night	17% 16% 33% 26% 7% 1	800
	21st to end	Night	25% 13% 28% 28% 6%	800
December	1st to 10th	Night	22% 12% 39% 22% 4	825
	11th to 20th	Night	24% 10% 35% 24% 6% 1	1000
	21st to end	Night	30% 15% 30% 21% 4	1100

Page generated at 2025-02-03 02:05:49. Version ac07

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