Milo McIver State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Milo McIver State Park clear sky chart from 2005-11-06 to 2024-01-13.

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	22% 9% 3 6% 5% 3 4 4 4 5% 34%	74751
	Night	24% 10% 3 6% 5% 3 4 4 4 5% 33%	75015
Transparency	Day	52% 6% 10% 17% 12% 3	74454
	Night	54% 6% 10% 15% 11% 4	74833
Seeing	Day	25% 12% 23% 26% 12% 2	13506
	Night	29% 9% 17% 27% 16% 2	22605

By Month

Percentage Cloud Cover SW (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	37% 13% 4 9% 6% 3 3 4 3 4 14%	1519
	11th to 20th	Day	34% 11% 4 6% 5% 2 4 4 4 4 23%	1459
	21st to end	Day	28% 11% 3 5% 6% 3 4 3 5% 5% 26%	1719
February	1st to 10th	Day	31% 14% 4 5% 5% 3 4 5% 5% 5% 19%	1620
	11th to 20th	Day	28% 14% 4 8% 7% 3 4 3 4 4 20%	1575
	21st to end	Day	29% 17% 4 7% 5% 3 5% 3 3 5% 19%	1422
March	1st to 10th	Day	28% 12% 5% 7% 7% 3 6% 4 5% 6% 17%	1866
	11th to 20th	Day	29% 14% 5% 6% 6% 4 5% 4 4 4 20%	1980
	21st to end	Day	31% 14% 5% 9% 6% 3 5% 5% 3 5% 13%	2236
April	1st to 10th	Day	30% 15% 5% 8% 6% 3 4 3 4 5% 17%	2160
	11th to 20th	Day	26% 14% 4 8% 6% 3 4 4 4 4 23%	2129
	21st to end	Day	26% 11% 4 7% 6% 3 4 4 6% 6% 24%	2308
May	1st to 10th	Day	23% 10% 4 6% 5% 4 4 4 4 4 33%	2492
	11th to 20th	Day	23% 8% 4 7% 5% 3 4 5% 5% 7% 29%	2477
	21st to end	Day	30% 9% 3 6% 4 3 4 4 5% 6% 25%	2723
June	1st to 10th	Day	26% 9% 3 6% 5% 3 4 3 5% 6% 30%	2520
	11th to 20th	Day	26% 10% 3 7% 6% 3 5% 5% 6% 6% 24%	2520
	21st to end	Day	11% 5% 2 5% 5% 3 4 4 3 6% 51%	2520
July	1st to 10th	Day	7% 4 2 4 4 2 4 5% 5% 6% 58%	2520
	11th to 20th	Day	8% 3 1 3 3 2 3 3 4 6% 62%	2520
	21st to end	Day	7% 3 1 2 2 2 3 2 3 5% 71%	2741
August	1st to 10th	Day	5% 4 2 3 4 3 4 4 3 6% 62%	2371
	11th to 20th	Day	5% 3 1 3 3 2 3 3 4 6% 66%	2298
	21st to end	Day	8% 5% 2 4 3 2 4 4 5% 7% 55%	2430
September	1st to 10th	Day	9% 4 2 3 4 2 3 3 4 7% 61%	2160
	11th to 20th	Day	13% 7% 3 6% 4 3 4 5% 4 6% 44%	2160
	21st to end	Day	18% 6% 2 5% 4 3 4 4 4 6% 44%	1904
October	1st to 10th	Day	21% 7% 3 4 4 3 4 5% 4 5% 39%	1800
	11th to 20th	Day	22% 6% 3 6% 5% 3 4 4 5% 6% 36%	1800
	21st to end	Day	29% 8% 3 5% 5% 4 3 4 3 5% 30%	1922
November	1st to 10th	Day	32% 9% 4 8% 5% 3 4 4 5% 6% 19%	1598
	11th to 20th	Day	34% 8% 4 7% 6% 3 3 5% 5% 5% 20%	1520
	21st to end	Day	29% 10% 5% 6% 5% 3 4 5% 4 4 24%	1520
December	1st to 10th	Day	27% 11% 4 7% 5% 3 4 4 4 4 27%	1520
	11th to 20th	Day	30% 12% 3 5% 6% 3 4 4 6% 5% 20%	1928
	21st to end	Day	31% 17% 4 7% 6% 3 3 4 4 4 18%	2794
January	1st to 10th	Night	34% 14% 4 7% 5% 3 4 3 3 4 18%	2646
	11th to 20th	Night	33% 13% 4 6% 4 2 3 3 4 5% 21%	2562
	21st to end	Night	28% 11% 4 6% 5% 3 3 3 4 5% 25%	2635
February	1st to 10th	Night	30% 15% 4 7% 5% 3 4 3 4 5% 19%	2340
	11th to 20th	Night	31% 14% 3 6% 4 2 4 3 4 5% 24%	2272
	21st to end	Night	30% 17% 4 5% 5% 2 4 3 3 6% 19%	1834
March	1st to 10th	Night	25% 14% 4 6% 6% 3 4 3 4 6% 24%	2092
	11th to 20th	Night	28% 10% 3 6% 5% 3 6% 5% 4 6% 24%	1980
	21st to end	Night	29% 17% 5% 7% 5% 3 4 4 4 5% 16%	2119
April	1st to 10th	Night	29% 16% 4 6% 6% 3 5% 4 3 5% 20%	1800
	11th to 20th	Night	24% 12% 4 6% 5% 3 4 4 4 6% 27%	1779
	21st to end	Night	29% 11% 3 6% 4 2 4 4 4 5% 26%	1650
May	1st to 10th	Night	25% 10% 3 5% 4 2 3 4 5% 6% 34%	1466
	11th to 20th	Night	23% 8% 2 7% 6% 3 4 5% 5% 9% 29%	1416
	21st to end	Night	25% 8% 3 6% 5% 4 5% 4 6% 7% 27%	1552
June	1st to 10th	Night	22% 9% 4 6% 3 3 5% 3 4 7% 35%	1440
	11th to 20th	Night	25% 10% 4 7% 5% 3 3 4 4 5% 30%	1440
	21st to end	Night	13% 5% 3 4 4 2 3 4 4 5% 53%	1440
July	1st to 10th	Night	9% 5% 2 3 3 2 3 3 4 5% 61%	1440
	11th to 20th	Night	6% 3 2 4 3 2 3 3 4 5% 65%	1440
	21st to end	Night	3 2 1 2 2 1 2 3 3 5% 74%	1576
August	1st to 10th	Night	6% 3 1 3 2 2 3 2 4 9% 65%	1565
	11th to 20th	Night	5% 3 1 3 3 2 4 3 3 5% 68%	1602
	21st to end	Night	8% 4 2 3 3 2 4 3 3 6% 62%	1926
September	1st to 10th	Night	9% 4 1 3 3 2 2 3 4 5% 65%	1800
	11th to 20th	Night	13% 6% 2 5% 5% 3 4 3 4 6% 49%	1800
	21st to end	Night	16% 6% 2 4 4 3 4 3 6% 7% 46%	2052
October	1st to 10th	Night	22% 7% 3 5% 4 2 3 3 3 5% 44%	2160
	11th to 20th	Night	20% 8% 3 6% 4 2 3 4 5% 6% 39%	2160
	21st to end	Night	27% 8% 2 6% 5% 2 3 4 4 5% 35%	2432
November	1st to 10th	Night	33% 10% 3 7% 6% 3 4 4 4 5% 22%	2481
	11th to 20th	Night	35% 10% 3 6% 5% 3 4 4 4 4 22%	2660
	21st to end	Night	28% 10% 3 6% 5% 3 4 4 4 5% 28%	2660
December	1st to 10th	Night	30% 9% 4 6% 5% 3 4 3 4 6% 27%	2660
	11th to 20th	Night	30% 13% 3 6% 6% 3 4 3 5% 7% 20%	3276
	21st to end	Night	29% 15% 5% 7% 6% 4 4 5% 4 4 18%	4862

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	75% 5% 7% 8% 5% 1	1519
	11th to 20th	Day	66% 5% 7% 9% 6% 6%	1459
	21st to end	Day	61% 5% 8% 13% 10% 3	1719
February	1st to 10th	Day	68% 7% 9% 9% 6% 1	1620
	11th to 20th	Day	70% 5% 7% 10% 5% 3	1584
	21st to end	Day	71% 5% 8% 8% 7% 2	1422
March	1st to 10th	Day	67% 8% 8% 11% 5% 1	1866
	11th to 20th	Day	68% 6% 7% 12% 6% 1	1980
	21st to end	Day	75% 7% 8% 8% 1	2236
April	1st to 10th	Day	71% 7% 8% 10% 4	2160
	11th to 20th	Day	66% 6% 8% 11% 7% 2	2132
	21st to end	Day	63% 8% 10% 11% 7% 2	2308
May	1st to 10th	Day	56% 5% 12% 18% 8%	2492
	11th to 20th	Day	57% 7% 11% 17% 6% 1	2480
	21st to end	Day	60% 8% 12% 16% 3	2724
June	1st to 10th	Day	57% 6% 15% 17% 5%	2520
	11th to 20th	Day	60% 8% 15% 11% 5%	2520
	21st to end	Day	37% 4 16% 27% 11% 5%	2520
July	1st to 10th	Day	27% 7% 14% 24% 21% 7%	2451
	11th to 20th	Day	24% 5% 9% 25% 31% 7%	2445
	21st to end	Day	17% 4 6% 30% 37% 7%	2589
August	1st to 10th	Day	23% 5% 13% 33% 19% 7%	2354
	11th to 20th	Day	20% 5% 13% 32% 22% 8%	2298
	21st to end	Day	29% 6% 10% 28% 23% 5%	2430
September	1st to 10th	Day	25% 4 9% 28% 21% 13%	2160
	11th to 20th	Day	40% 6% 10% 19% 16% 8%	2160
	21st to end	Day	42% 5% 11% 19% 15% 8%	1904
October	1st to 10th	Day	46% 6% 9% 20% 14% 5%	1800
	11th to 20th	Day	50% 5% 11% 15% 15% 4	1800
	21st to end	Day	57% 6% 6% 15% 14% 1	1922
November	1st to 10th	Day	66% 6% 9% 13% 5% 1	1598
	11th to 20th	Day	65% 8% 8% 10% 7% 2	1520
	21st to end	Day	64% 6% 6% 7% 16% 2	1520
December	1st to 10th	Day	62% 6% 8% 10% 11% 4	1520
	11th to 20th	Day	65% 7% 10% 10% 8%	1928
	21st to end	Day	71% 6% 9% 10% 3 1	2794
January	1st to 10th	Night	72% 4 8% 8% 6% 2	2646
	11th to 20th	Night	65% 4 9% 10% 7% 5%	2562
	21st to end	Night	62% 5% 6% 12% 10% 4	2635
February	1st to 10th	Night	68% 6% 9% 9% 6% 2	2340
	11th to 20th	Night	65% 6% 8% 12% 7% 3	2274
	21st to end	Night	68% 6% 7% 9% 7% 2	1834
March	1st to 10th	Night	63% 6% 9% 15% 5% 1	2092
	11th to 20th	Night	62% 7% 9% 14% 6% 2	1980
	21st to end	Night	71% 7% 10% 10% 2	2119
April	1st to 10th	Night	69% 6% 10% 10% 4	1800
	11th to 20th	Night	61% 8% 11% 11% 6% 3	1779
	21st to end	Night	62% 6% 12% 12% 6% 3	1650
May	1st to 10th	Night	53% 6% 11% 20% 8% 2	1466
	11th to 20th	Night	55% 8% 12% 17% 5% 3	1416
	21st to end	Night	57% 10% 12% 16% 4	1552
June	1st to 10th	Night	53% 7% 17% 18% 5%	1440
	11th to 20th	Night	59% 6% 15% 16% 4 1	1440
	21st to end	Night	35% 7% 16% 26% 10% 5%	1440
July	1st to 10th	Night	27% 7% 10% 27% 22% 7%	1400
	11th to 20th	Night	24% 5% 11% 24% 28% 9%	1392
	21st to end	Night	14% 4 7% 31% 35% 10%	1488
August	1st to 10th	Night	20% 5% 13% 36% 18% 8%	1557
	11th to 20th	Night	21% 4 13% 31% 22% 9%	1602
	21st to end	Night	25% 6% 11% 31% 20% 6%	1926
September	1st to 10th	Night	24% 5% 12% 27% 19% 13%	1800
	11th to 20th	Night	39% 6% 9% 22% 12% 12%	1800
	21st to end	Night	38% 8% 12% 17% 16% 10%	2052
October	1st to 10th	Night	45% 4 7% 19% 18% 6%	2160
	11th to 20th	Night	47% 7% 8% 16% 18% 5%	2160
	21st to end	Night	54% 6% 7% 13% 17% 5%	2432
November	1st to 10th	Night	65% 6% 7% 11% 9% 1	2481
	11th to 20th	Night	65% 8% 7% 9% 8% 3	2660
	21st to end	Night	59% 5% 7% 10% 14% 5%	2660
December	1st to 10th	Night	60% 5% 9% 12% 11% 2	2660
	11th to 20th	Night	65% 6% 10% 10% 8% 1	3276
	21st to end	Night	66% 11% 8% 10% 4 1	4862

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	48% 16% 15% 16% 6%	180
	11th to 20th	Day	42% 10% 30% 10% 7% 1	165
	21st to end	Day	38% 11% 19% 21% 9% 1	311
February	1st to 10th	Day	43% 14% 16% 21% 6%	340
	11th to 20th	Day	37% 16% 27% 17% 3 1	335
	21st to end	Day	39% 16% 23% 18% 3	320
March	1st to 10th	Day	35% 17% 28% 15% 6%	420
	11th to 20th	Day	34% 17% 22% 20% 6%	420
	21st to end	Day	38% 18% 21% 17% 5%	462
April	1st to 10th	Day	40% 15% 19% 18% 6% 1	420
	11th to 20th	Day	33% 18% 27% 14% 5% 2	412
	21st to end	Day	28% 16% 28% 19% 7% 1	420
May	1st to 10th	Day	23% 16% 26% 23% 8% 3	423
	11th to 20th	Day	32% 13% 20% 23% 10% 2	448
	21st to end	Day	28% 9% 23% 25% 12% 2	485
June	1st to 10th	Day	26% 11% 20% 27% 14% 3	450
	11th to 20th	Day	25% 15% 27% 23% 9% 1	450
	21st to end	Day	11% 6% 27% 36% 16% 3	450
July	1st to 10th	Day	8% 5% 24% 43% 17% 3	446
	11th to 20th	Day	5% 8% 27% 40% 18% 3	444
	21st to end	Day	6% 3 20% 46% 20% 6%	487
August	1st to 10th	Day	6% 5% 16% 49% 17% 7%	447
	11th to 20th	Day	4 5% 21% 38% 27% 6%	437
	21st to end	Day	8% 8% 27% 37% 16% 4	495
September	1st to 10th	Day	10% 8% 28% 34% 18% 3	450
	11th to 20th	Day	16% 9% 21% 33% 19% 2	450
	21st to end	Day	20% 10% 25% 31% 13% 1	450
October	1st to 10th	Day	23% 12% 22% 26% 16% 2	450
	11th to 20th	Day	26% 11% 20% 26% 15% 1	450
	21st to end	Day	34% 13% 20% 20% 11% 2	437
November	1st to 10th	Day	35% 17% 18% 24% 6% 1	234
	11th to 20th	Day	33% 14% 27% 16% 9% 2	180
	21st to end	Day	32% 16% 21% 21% 11%	180
December	1st to 10th	Day	37% 15% 20% 18% 9% 1	180
	11th to 20th	Day	47% 13% 22% 12% 6%	180
	21st to end	Day	46% 14% 18% 14% 8%	198
January	1st to 10th	Night	44% 14% 20% 16% 6% 1	760
	11th to 20th	Night	40% 11% 21% 19% 9%	732
	21st to end	Night	35% 9% 23% 24% 7% 1	792
February	1st to 10th	Night	38% 11% 19% 26% 5% 1	720
	11th to 20th	Night	39% 11% 17% 24% 8%	704
	21st to end	Night	41% 13% 18% 22% 5%	592
March	1st to 10th	Night	34% 13% 19% 24% 10% 1	720
	11th to 20th	Night	33% 11% 20% 27% 9%	720
	21st to end	Night	39% 12% 16% 22% 10% 1	792
April	1st to 10th	Night	38% 9% 17% 23% 11% 1	720
	11th to 20th	Night	32% 9% 18% 24% 14% 2	711
	21st to end	Night	36% 10% 12% 30% 12% 1	570
May	1st to 10th	Night	27% 10% 13% 32% 16% 2	386
	11th to 20th	Night	25% 7% 13% 30% 25% 1	354
	21st to end	Night	29% 5% 17% 27% 20% 2	389
June	1st to 10th	Night	28% 5% 16% 29% 21% 1	360
	11th to 20th	Night	28% 9% 16% 31% 16% 1	360
	21st to end	Night	14% 5% 14% 40% 26% 1	360
July	1st to 10th	Night	9% 3 9% 40% 39% 1	350
	11th to 20th	Night	7% 1 14% 47% 30% 1	348
	21st to end	Night	4 2 7% 45% 39% 3	394
August	1st to 10th	Night	7% 2 7% 32% 46% 7%	491
	11th to 20th	Night	6% 1 8% 31% 46% 8%	534
	21st to end	Night	9% 4 14% 40% 30% 4	738
September	1st to 10th	Night	11% 3 16% 36% 31% 2	720
	11th to 20th	Night	14% 5% 12% 33% 31% 5%	720
	21st to end	Night	19% 5% 15% 33% 26% 3	720
October	1st to 10th	Night	25% 5% 15% 33% 20% 3	720
	11th to 20th	Night	24% 8% 14% 33% 19% 2	720
	21st to end	Night	31% 10% 21% 25% 11% 3	792
November	1st to 10th	Night	39% 10% 18% 27% 6%	740
	11th to 20th	Night	41% 11% 22% 21% 6%	760
	21st to end	Night	33% 11% 22% 28% 6%	760
December	1st to 10th	Night	35% 11% 23% 24% 6% 1	760
	11th to 20th	Night	41% 12% 21% 20% 6%	760
	21st to end	Night	44% 13% 22% 16% 4 1	836

Page generated at 2024-01-10 16:35:26. Version ac07

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