Maple Plains
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Maple Plains clear sky chart from 2005-11-06 to 2024-01-16.

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	18% 10% 4 7% 6% 3 5% 5% 5% 7% 31%	74967
	Night	20% 11% 4 8% 6% 3 4 4 5% 6% 29%	74813
Transparency	Day	36% 39% 9% 12% 4	74662
	Night	37% 39% 9% 11% 4	74653
Seeing	Day	22% 10% 29% 27% 11% 2	16027
	Night	24% 12% 30% 26% 8% 1	23523

By Month

Percentage Cloud Cover NE (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	15% 16% 8% 12% 6% 4 5% 4 4 5% 22%	1352
	11th to 20th	Day	20% 14% 5% 10% 8% 4 6% 5% 4 5% 19%	1481
	21st to end	Day	13% 8% 4 9% 7% 5% 6% 6% 5% 5% 32%	1755
February	1st to 10th	Day	17% 11% 4 9% 5% 4 4 5% 5% 5% 32%	1620
	11th to 20th	Day	17% 14% 4 7% 6% 4 5% 5% 4 5% 29%	1573
	21st to end	Day	11% 9% 6% 7% 6% 3 6% 4 6% 8% 32%	1355
March	1st to 10th	Day	16% 11% 6% 8% 6% 4 5% 5% 5% 6% 29%	1927
	11th to 20th	Day	12% 10% 6% 11% 8% 4 4 5% 4 5% 30%	1980
	21st to end	Day	17% 13% 6% 9% 6% 4 4 3 4 5% 30%	2195
April	1st to 10th	Day	19% 12% 4 7% 5% 3 5% 4 4 6% 30%	2160
	11th to 20th	Day	19% 11% 3 5% 5% 3 4 4 5% 7% 34%	2205
	21st to end	Day	21% 11% 4 6% 5% 3 4 5% 5% 6% 29%	2340
May	1st to 10th	Day	25% 10% 3 7% 5% 4 5% 4 4 6% 27%	2461
	11th to 20th	Day	21% 9% 4 6% 5% 3 4 4 4 6% 34%	2478
	21st to end	Day	19% 9% 3 6% 5% 3 4 5% 5% 7% 34%	2724
June	1st to 10th	Day	25% 10% 3 6% 6% 3 6% 4 5% 6% 26%	2563
	11th to 20th	Day	21% 9% 3 6% 5% 3 4 4 5% 7% 34%	2700
	21st to end	Day	24% 8% 3 6% 5% 3 4 4 5% 7% 31%	2700
July	1st to 10th	Day	16% 5% 3 5% 4 3 5% 5% 6% 10% 38%	2700
	11th to 20th	Day	15% 6% 2 5% 5% 3 6% 5% 8% 9% 37%	2569
	21st to end	Day	18% 7% 3 6% 6% 3 6% 5% 6% 8% 31%	2745
August	1st to 10th	Day	14% 7% 2 5% 5% 3 4 6% 6% 9% 39%	2342
	11th to 20th	Day	16% 7% 2 6% 5% 4 5% 6% 6% 9% 34%	2304
	21st to end	Day	14% 6% 2 4 5% 3 5% 5% 6% 8% 43%	2480
September	1st to 10th	Day	17% 5% 2 4 5% 3 4 5% 6% 9% 41%	2160
	11th to 20th	Day	19% 8% 3 6% 5% 3 4 4 4 7% 38%	2124
	21st to end	Day	18% 7% 2 5% 5% 3 4 4 4 7% 41%	1904
October	1st to 10th	Day	18% 8% 3 5% 6% 3 4 5% 5% 8% 35%	1800
	11th to 20th	Day	19% 10% 5% 7% 6% 4 5% 5% 5% 8% 26%	1800
	21st to end	Day	18% 13% 4 9% 8% 4 5% 4 4 7% 23%	1940
November	1st to 10th	Day	20% 13% 4 8% 6% 4 6% 5% 5% 5% 26%	1505
	11th to 20th	Day	20% 14% 5% 9% 7% 4 5% 4 5% 7% 21%	1520
	21st to end	Day	18% 14% 5% 11% 7% 4 6% 6% 5% 6% 18%	1520
December	1st to 10th	Day	22% 14% 6% 9% 6% 4 5% 4 5% 6% 17%	1520
	11th to 20th	Day	21% 16% 7% 10% 8% 4 6% 4 4 4 16%	1906
	21st to end	Day	18% 13% 6% 14% 7% 4 4 4 4 6% 18%	2559
January	1st to 10th	Night	18% 14% 5% 10% 7% 4 5% 5% 5% 5% 23%	2805
	11th to 20th	Night	18% 14% 5% 9% 6% 4 5% 4 4 6% 24%	2601
	21st to end	Night	14% 10% 5% 8% 6% 3 6% 5% 5% 7% 30%	2598
February	1st to 10th	Night	17% 12% 5% 7% 6% 3 4 4 5% 6% 30%	2340
	11th to 20th	Night	18% 14% 5% 8% 8% 3 5% 4 4 5% 24%	2273
	21st to end	Night	12% 12% 5% 8% 7% 4 5% 4 5% 5% 32%	1900
March	1st to 10th	Night	16% 13% 5% 8% 7% 3 4 4 4 6% 28%	2017
	11th to 20th	Night	18% 10% 5% 8% 7% 4 4 5% 4 6% 29%	1979
	21st to end	Night	19% 13% 5% 9% 5% 3 3 4 4 4 32%	2160
April	1st to 10th	Night	23% 11% 5% 8% 6% 4 4 5% 5% 6% 25%	1800
	11th to 20th	Night	21% 12% 4 5% 5% 3 4 3 4 6% 33%	1702
	21st to end	Night	24% 12% 4 7% 5% 3 3 4 4 5% 29%	1620
May	1st to 10th	Night	24% 9% 3 7% 4 3 5% 4 4 5% 32%	1497
	11th to 20th	Night	21% 7% 2 7% 5% 3 5% 3 5% 6% 35%	1416
	21st to end	Night	15% 8% 3 7% 6% 4 4 5% 5% 9% 34%	1550
June	1st to 10th	Night	27% 8% 4 6% 6% 4 4 5% 4 5% 27%	1410
	11th to 20th	Night	19% 8% 3 5% 5% 3 3 4 4 7% 38%	1260
	21st to end	Night	22% 9% 4 7% 5% 2 4 5% 5% 7% 29%	1260
July	1st to 10th	Night	15% 7% 2 6% 5% 3 6% 5% 6% 8% 35%	1260
	11th to 20th	Night	14% 7% 3 4 8% 3 5% 7% 7% 8% 34%	1372
	21st to end	Night	16% 7% 3 7% 6% 4 6% 5% 5% 8% 32%	1573
August	1st to 10th	Night	15% 5% 2 5% 6% 4 6% 5% 6% 7% 39%	1594
	11th to 20th	Night	15% 7% 3 7% 6% 4 4 5% 6% 8% 34%	1596
	21st to end	Night	14% 5% 2 6% 5% 3 5% 5% 6% 9% 41%	1876
September	1st to 10th	Night	16% 6% 3 5% 5% 3 4 4 4 8% 43%	1800
	11th to 20th	Night	18% 6% 3 5% 5% 3 4 4 4 6% 43%	1835
	21st to end	Night	18% 6% 2 4 4 3 4 4 5% 7% 43%	2056
October	1st to 10th	Night	20% 6% 2 6% 5% 3 4 4 5% 6% 39%	2160
	11th to 20th	Night	19% 8% 4 6% 5% 3 4 5% 5% 6% 35%	2160
	21st to end	Night	24% 11% 3 8% 6% 3 5% 4 4 5% 27%	2415
November	1st to 10th	Night	23% 11% 3 6% 5% 3 5% 5% 5% 6% 29%	2570
	11th to 20th	Night	21% 11% 5% 9% 5% 4 5% 4 5% 6% 25%	2660
	21st to end	Night	23% 14% 4 8% 6% 3 4 4 5% 6% 22%	2660
December	1st to 10th	Night	24% 12% 6% 10% 8% 3 5% 5% 6% 5% 16%	2660
	11th to 20th	Night	25% 16% 5% 8% 7% 4 4 4 4 5% 18%	3293
	21st to end	Night	24% 16% 5% 11% 6% 3 4 4 4 4 20%	5085

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	46% 43% 6% 5% 1	1353
	11th to 20th	Day	42% 44% 5% 7% 2	1481
	21st to end	Day	35% 40% 9% 8% 7%	1755
February	1st to 10th	Day	38% 37% 10% 9% 6%	1620
	11th to 20th	Day	40% 38% 9% 10% 3 1	1581
	21st to end	Day	36% 39% 9% 10% 5% 1	1355
March	1st to 10th	Day	39% 38% 7% 11% 4	1931
	11th to 20th	Day	36% 37% 8% 13% 4 1	1980
	21st to end	Day	39% 37% 8% 10% 5% 1	2195
April	1st to 10th	Day	36% 38% 8% 12% 6% 1	2160
	11th to 20th	Day	32% 37% 7% 14% 9% 1	2205
	21st to end	Day	34% 38% 9% 11% 7% 1	2340
May	1st to 10th	Day	38% 38% 7% 10% 7% 1	2461
	11th to 20th	Day	33% 39% 8% 14% 6%	2482
	21st to end	Day	31% 39% 10% 14% 6%	2724
June	1st to 10th	Day	40% 38% 9% 10% 2	2563
	11th to 20th	Day	33% 39% 8% 14% 6% 1	2700
	21st to end	Day	38% 38% 9% 10% 4 1	2700
July	1st to 10th	Day	28% 41% 11% 16% 4	2625
	11th to 20th	Day	28% 41% 12% 13% 6%	2490
	21st to end	Day	32% 42% 10% 13% 3	2592
August	1st to 10th	Day	31% 39% 10% 15% 4	2328
	11th to 20th	Day	30% 41% 11% 16% 3	2304
	21st to end	Day	26% 39% 12% 18% 6%	2480
September	1st to 10th	Day	29% 39% 11% 16% 6%	2160
	11th to 20th	Day	32% 37% 8% 15% 8%	2124
	21st to end	Day	31% 37% 8% 18% 6%	1904
October	1st to 10th	Day	32% 39% 10% 15% 4	1800
	11th to 20th	Day	37% 40% 10% 11% 2	1800
	21st to end	Day	41% 40% 7% 7% 4	1940
November	1st to 10th	Day	37% 44% 7% 9% 3	1505
	11th to 20th	Day	37% 44% 9% 8% 2	1520
	21st to end	Day	40% 45% 10% 5% 1	1520
December	1st to 10th	Day	44% 43% 8% 4 1	1520
	11th to 20th	Day	54% 36% 5% 3 1	1905
	21st to end	Day	54% 28% 10% 6% 1	2559
January	1st to 10th	Night	41% 43% 8% 7% 1	2805
	11th to 20th	Night	39% 44% 8% 7% 2	2601
	21st to end	Night	34% 40% 9% 12% 5% 1	2598
February	1st to 10th	Night	36% 38% 9% 10% 6% 1	2340
	11th to 20th	Night	41% 39% 7% 7% 5% 1	2276
	21st to end	Night	37% 38% 9% 12% 4 1	1900
March	1st to 10th	Night	41% 38% 7% 10% 5% 1	2026
	11th to 20th	Night	37% 38% 7% 13% 3 1	1980
	21st to end	Night	37% 37% 7% 11% 6% 1	2160
April	1st to 10th	Night	39% 39% 7% 7% 6% 1	1800
	11th to 20th	Night	35% 36% 7% 13% 9% 1	1702
	21st to end	Night	37% 37% 6% 9% 9% 1	1620
May	1st to 10th	Night	36% 38% 7% 12% 5% 1	1497
	11th to 20th	Night	32% 39% 7% 14% 6% 1	1417
	21st to end	Night	30% 40% 9% 15% 5%	1551
June	1st to 10th	Night	41% 39% 7% 9% 4	1410
	11th to 20th	Night	32% 39% 8% 14% 7%	1260
	21st to end	Night	40% 40% 10% 6% 4	1260
July	1st to 10th	Night	29% 40% 11% 16% 4	1225
	11th to 20th	Night	32% 41% 12% 11% 4	1328
	21st to end	Night	33% 42% 11% 10% 4	1486
August	1st to 10th	Night	30% 40% 9% 16% 5%	1583
	11th to 20th	Night	32% 39% 12% 15% 2	1596
	21st to end	Night	26% 40% 13% 16% 5%	1876
September	1st to 10th	Night	28% 39% 10% 17% 6%	1800
	11th to 20th	Night	28% 38% 8% 17% 8%	1835
	21st to end	Night	28% 38% 9% 17% 7% 1	2056
October	1st to 10th	Night	29% 39% 10% 16% 6%	2160
	11th to 20th	Night	33% 39% 12% 13% 3	2160
	21st to end	Night	40% 40% 7% 8% 5%	2415
November	1st to 10th	Night	35% 43% 9% 10% 4	2570
	11th to 20th	Night	36% 44% 8% 8% 3	2660
	21st to end	Night	37% 45% 10% 6% 2	2660
December	1st to 10th	Night	44% 43% 7% 5% 2	2660
	11th to 20th	Night	52% 35% 5% 6% 1	3295
	21st to end	Night	54% 29% 9% 6% 2	5085

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	21% 20% 33% 20% 5%	205
	11th to 20th	Day	26% 14% 34% 20% 6% 1	356
	21st to end	Day	17% 11% 39% 28% 5% 1	374
February	1st to 10th	Day	27% 12% 36% 20% 4 1	340
	11th to 20th	Day	24% 15% 34% 22% 5%	336
	21st to end	Day	17% 12% 33% 30% 8% 1	280
March	1st to 10th	Day	22% 11% 33% 28% 5% 1	399
	11th to 20th	Day	17% 13% 35% 26% 8% 1	420
	21st to end	Day	24% 14% 28% 24% 10% 1	462
April	1st to 10th	Day	27% 13% 34% 20% 6%	420
	11th to 20th	Day	21% 12% 33% 23% 9% 2	412
	21st to end	Day	24% 10% 26% 25% 13% 1	420
May	1st to 10th	Day	31% 7% 31% 22% 8% 2	544
	11th to 20th	Day	23% 6% 27% 29% 13% 2	624
	21st to end	Day	23% 9% 29% 27% 11% 1	680
June	1st to 10th	Day	31% 6% 24% 27% 11% 1	630
	11th to 20th	Day	21% 5% 27% 33% 11% 2	630
	21st to end	Day	25% 3 23% 33% 13% 3	630
July	1st to 10th	Day	19% 4 27% 32% 15% 3	620
	11th to 20th	Day	17% 5% 22% 35% 18% 3	618
	21st to end	Day	18% 5% 19% 39% 17% 2	685
August	1st to 10th	Day	12% 5% 21% 41% 18% 4	461
	11th to 20th	Day	18% 3 23% 33% 18% 6%	439
	21st to end	Day	15% 6% 23% 33% 19% 4	495
September	1st to 10th	Day	15% 5% 30% 33% 15% 3	450
	11th to 20th	Day	23% 8% 26% 28% 14% 2	450
	21st to end	Day	18% 10% 29% 26% 13% 3	412
October	1st to 10th	Day	18% 12% 25% 24% 19% 2	360
	11th to 20th	Day	22% 16% 27% 22% 12% 2	360
	21st to end	Day	21% 18% 32% 21% 7% 1	396
November	1st to 10th	Day	22% 18% 32% 21% 5% 1	365
	11th to 20th	Day	30% 18% 29% 17% 5% 1	370
	21st to end	Day	25% 19% 35% 18% 3	370
December	1st to 10th	Day	30% 15% 34% 19% 3	370
	11th to 20th	Day	28% 24% 34% 13% 2	370
	21st to end	Day	23% 19% 36% 18% 3 1	274
January	1st to 10th	Night	25% 15% 35% 20% 5%	850
	11th to 20th	Night	24% 16% 32% 21% 5%	829
	21st to end	Night	19% 13% 36% 24% 7% 1	802
February	1st to 10th	Night	24% 14% 34% 23% 5%	720
	11th to 20th	Night	24% 13% 38% 21% 4 1	703
	21st to end	Night	19% 10% 34% 27% 9% 1	592
March	1st to 10th	Night	22% 10% 37% 28% 3	720
	11th to 20th	Night	20% 13% 29% 29% 8% 1	720
	21st to end	Night	26% 11% 27% 26% 10% 1	774
April	1st to 10th	Night	27% 10% 32% 25% 5%	540
	11th to 20th	Night	27% 7% 31% 26% 9% 1	534
	21st to end	Night	28% 8% 29% 26% 8% 1	540
May	1st to 10th	Night	29% 6% 30% 24% 9% 2	540
	11th to 20th	Night	22% 7% 28% 30% 11% 2	532
	21st to end	Night	19% 8% 37% 30% 6%	583
June	1st to 10th	Night	28% 8% 27% 29% 7% 1	510
	11th to 20th	Night	21% 5% 26% 38% 10% 1	360
	21st to end	Night	26% 3 26% 35% 9% 1	360
July	1st to 10th	Night	18% 4 29% 35% 13% 1	350
	11th to 20th	Night	14% 4 30% 40% 11% 1	458
	21st to end	Night	17% 5% 23% 41% 15%	590
August	1st to 10th	Night	16% 3 28% 37% 17% 1	538
	11th to 20th	Night	16% 4 26% 35% 18% 1	532
	21st to end	Night	16% 6% 22% 36% 19% 2	594
September	1st to 10th	Night	17% 6% 31% 33% 12% 1	540
	11th to 20th	Night	21% 9% 21% 37% 13% 1	575
	21st to end	Night	20% 10% 30% 31% 9% 1	720
October	1st to 10th	Night	22% 9% 28% 29% 11%	720
	11th to 20th	Night	22% 12% 31% 25% 9% 1	720
	21st to end	Night	30% 17% 27% 20% 5%	812
November	1st to 10th	Night	29% 16% 31% 20% 5% 1	830
	11th to 20th	Night	26% 20% 27% 21% 5% 1	850
	21st to end	Night	30% 19% 27% 20% 3	850
December	1st to 10th	Night	29% 19% 31% 17% 4	850
	11th to 20th	Night	26% 23% 31% 16% 3	850
	21st to end	Night	30% 16% 31% 19% 4 1	935

Page generated at 2024-01-13 10:37:54. Version ac07

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