Marquette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marquette clear sky chart from 2005-11-06 to 2024-11-03.

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	13% 10% 4 9% 6% 5% 5% 4 6% 7% 33%	101172
	Night	14% 12% 5% 10% 6% 5% 4 3 5% 6% 30%	97857
Transparency	Day	27% 50% 7% 11% 5%	100929
	Night	29% 50% 7% 10% 4	97719
Seeing	Day	18% 15% 34% 23% 8% 2	15905
	Night	19% 13% 33% 25% 9% 1	25863

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	10% 17% 12% 15% 6% 5% 5% 4 5% 7% 14%	2527
	11th to 20th	Day	9% 15% 6% 18% 13% 8% 5% 3 7% 5% 11%	2530
	21st to end	Day	9% 18% 9% 16% 9% 7% 5% 4 5% 5% 14%	2783
February	1st to 10th	Day	9% 13% 4 14% 10% 7% 6% 3 5% 6% 21%	1571
	11th to 20th	Day	9% 12% 4 13% 9% 9% 6% 5% 6% 5% 22%	1799
	21st to end	Day	12% 12% 6% 13% 8% 6% 6% 4 6% 6% 21%	1570
March	1st to 10th	Day	10% 13% 6% 11% 6% 5% 4 4 4 6% 33%	3118
	11th to 20th	Day	8% 14% 7% 17% 9% 4 3 3 4 5% 26%	3249
	21st to end	Day	15% 12% 8% 13% 7% 6% 6% 4 6% 5% 17%	4157
April	1st to 10th	Day	14% 13% 5% 8% 6% 4 5% 4 5% 7% 29%	2280
	11th to 20th	Day	19% 13% 4 9% 4 4 4 3 5% 5% 29%	2296
	21st to end	Day	15% 11% 3 7% 5% 4 6% 5% 5% 7% 33%	2470
May	1st to 10th	Day	15% 8% 2 7% 4 4 4 3 5% 6% 42%	4265
	11th to 20th	Day	13% 9% 3 6% 4 4 4 4 5% 7% 42%	4399
	21st to end	Day	11% 7% 2 7% 5% 5% 5% 4 6% 8% 39%	4837
June	1st to 10th	Day	11% 8% 2 6% 5% 4 5% 4 6% 9% 39%	2660
	11th to 20th	Day	15% 6% 2 7% 4 4 5% 4 8% 7% 38%	2660
	21st to end	Day	15% 6% 2 7% 5% 4 4 5% 6% 9% 38%	2660
July	1st to 10th	Day	12% 5% 3 7% 5% 5% 4 4 6% 10% 39%	4440
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 6% 10% 49%	4440
	21st to end	Day	10% 5% 1 4 3 3 4 3 7% 8% 52%	4814
August	1st to 10th	Day	9% 5% 2 6% 4 5% 5% 5% 7% 9% 43%	4423
	11th to 20th	Day	14% 5% 2 5% 3 3 4 3 5% 7% 49%	4117
	21st to end	Day	15% 6% 2 5% 4 3 3 3 5% 7% 47%	4214
September	1st to 10th	Day	16% 6% 2 5% 4 4 5% 4 6% 7% 42%	2280
	11th to 20th	Day	14% 5% 3 5% 5% 4 5% 4 6% 8% 41%	2152
	21st to end	Day	19% 9% 3 6% 4 4 5% 4 6% 7% 33%	2090
October	1st to 10th	Day	18% 10% 3 6% 5% 5% 5% 5% 5% 7% 32%	2028
	11th to 20th	Day	23% 14% 3 9% 5% 4 6% 4 6% 6% 20%	1786
	21st to end	Day	20% 20% 5% 9% 6% 4 4 4 4 5% 18%	1881
November	1st to 10th	Day	16% 16% 4 9% 5% 4 3 4 6% 6% 26%	1690
	11th to 20th	Day	14% 17% 7% 12% 8% 5% 5% 3 6% 5% 17%	1663
	21st to end	Day	15% 19% 7% 15% 6% 4 4 3 4 5% 16%	1520
December	1st to 10th	Day	10% 15% 10% 18% 7% 6% 5% 4 4 5% 17%	1335
	11th to 20th	Day	14% 19% 7% 18% 6% 5% 4 4 4 4 14%	1685
	21st to end	Day	17% 23% 12% 17% 7% 6% 4 3 3 3 7%	2783
January	1st to 10th	Night	13% 18% 7% 20% 6% 5% 3 2 4 3 18%	4428
	11th to 20th	Night	9% 17% 7% 19% 9% 8% 6% 3 4 4 14%	4440
	21st to end	Night	12% 15% 8% 15% 8% 6% 5% 4 5% 6% 16%	4884
February	1st to 10th	Night	8% 15% 7% 12% 9% 7% 7% 4 5% 5% 21%	2608
	11th to 20th	Night	9% 13% 5% 14% 9% 6% 6% 5% 5% 6% 22%	2266
	21st to end	Night	13% 15% 6% 13% 8% 6% 5% 3 4 6% 22%	1884
March	1st to 10th	Night	10% 10% 5% 8% 5% 5% 4 3 5% 8% 36%	3722
	11th to 20th	Night	7% 14% 7% 14% 5% 5% 4 3 4 6% 31%	3709
	21st to end	Night	17% 11% 5% 12% 8% 5% 5% 3 6% 6% 22%	3503
April	1st to 10th	Night	17% 15% 3 9% 5% 4 4 5% 5% 5% 27%	1900
	11th to 20th	Night	22% 9% 4 6% 4 3 4 4 5% 5% 34%	1833
	21st to end	Night	15% 11% 3 8% 5% 4 5% 3 5% 6% 35%	1710
May	1st to 10th	Night	17% 8% 3 6% 3 4 3 3 5% 5% 43%	2678
	11th to 20th	Night	13% 8% 3 7% 4 4 5% 3 5% 6% 42%	2506
	21st to end	Night	18% 7% 2 7% 5% 5% 5% 5% 5% 7% 35%	2750
June	1st to 10th	Night	13% 6% 2 7% 5% 5% 4 4 5% 7% 42%	1520
	11th to 20th	Night	14% 7% 3 7% 5% 4 6% 5% 6% 7% 36%	1437
	21st to end	Night	16% 6% 3 6% 4 3 5% 4 6% 9% 39%	1520
July	1st to 10th	Night	11% 6% 3 8% 5% 5% 4 3 6% 7% 41%	2530
	11th to 20th	Night	7% 4 1 4 4 4 4 3 5% 8% 55%	2530
	21st to end	Night	10% 4 2 5% 4 3 3 2 5% 8% 54%	2750
August	1st to 10th	Night	10% 7% 2 7% 4 4 4 3 6% 6% 47%	2517
	11th to 20th	Night	15% 5% 2 5% 4 3 4 3 4 8% 49%	2714
	21st to end	Night	14% 6% 3 7% 4 3 4 3 4 6% 46%	3439
September	1st to 10th	Night	13% 5% 2 4 4 4 3 3 5% 8% 47%	1900
	11th to 20th	Night	13% 6% 2 6% 5% 4 5% 4 5% 6% 44%	2009
	21st to end	Night	18% 7% 2 6% 4 4 5% 4 5% 7% 37%	2090
October	1st to 10th	Night	18% 7% 2 7% 4 4 4 4 6% 7% 37%	2151
	11th to 20th	Night	18% 12% 3 7% 5% 5% 4 4 5% 7% 30%	2394
	21st to end	Night	20% 17% 4 9% 6% 4 4 4 5% 5% 22%	2717
November	1st to 10th	Night	14% 17% 4 8% 5% 6% 4 4 6% 7% 26%	2433
	11th to 20th	Night	16% 18% 7% 11% 6% 5% 4 3 4 4 21%	2512
	21st to end	Night	15% 17% 8% 13% 7% 4 4 3 5% 5% 18%	2660
December	1st to 10th	Night	11% 17% 9% 13% 8% 5% 5% 4 5% 5% 18%	2838
	11th to 20th	Night	13% 15% 7% 18% 7% 6% 5% 4 4 4 17%	3491
	21st to end	Night	18% 23% 12% 15% 5% 5% 4 3 3 3 9%	4884

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	45% 39% 10% 5%	2528
	11th to 20th	Day	45% 41% 6% 7%	2530
	21st to end	Day	44% 43% 9% 3	2783
February	1st to 10th	Day	21% 68% 4 4 2	1571
	11th to 20th	Day	23% 66% 4 5% 2	1809
	21st to end	Day	21% 66% 4 7% 3	1570
March	1st to 10th	Day	28% 42% 9% 15% 6%	3120
	11th to 20th	Day	40% 42% 8% 8% 2 1	3249
	21st to end	Day	43% 42% 6% 6% 3	4157
April	1st to 10th	Day	21% 66% 5% 6% 3	2280
	11th to 20th	Day	19% 66% 3 8% 3 1	2296
	21st to end	Day	17% 66% 4 8% 5%	2470
May	1st to 10th	Day	24% 40% 7% 17% 12% 1	4277
	11th to 20th	Day	23% 43% 8% 21% 6%	4403
	21st to end	Day	28% 42% 8% 10% 11% 1	4837
June	1st to 10th	Day	15% 66% 5% 8% 5% 1	2660
	11th to 20th	Day	17% 66% 5% 7% 5%	2660
	21st to end	Day	15% 65% 6% 9% 5% 1	2660
July	1st to 10th	Day	29% 41% 9% 13% 7% 1	4371
	11th to 20th	Day	19% 39% 10% 22% 9% 1	4365
	21st to end	Day	17% 39% 7% 25% 12%	4662
August	1st to 10th	Day	24% 40% 12% 19% 6%	4408
	11th to 20th	Day	24% 39% 10% 22% 5%	4157
	21st to end	Day	24% 39% 11% 17% 9%	4213
September	1st to 10th	Day	19% 62% 4 11% 4	2280
	11th to 20th	Day	14% 63% 9% 10% 4	2152
	21st to end	Day	19% 62% 7% 11% 2	2090
October	1st to 10th	Day	21% 62% 5% 8% 4	2028
	11th to 20th	Day	26% 60% 5% 5% 3	1786
	21st to end	Day	31% 60% 3 3 2	1881
November	1st to 10th	Day	27% 60% 6% 6% 2	1690
	11th to 20th	Day	28% 61% 4 4 2	1663
	21st to end	Day	30% 62% 4 2 2	1520
December	1st to 10th	Day	28% 61% 6% 3 1	1335
	11th to 20th	Day	40% 49% 5% 4 2	1685
	21st to end	Day	54% 41% 3 2 1	2783
January	1st to 10th	Night	48% 39% 5% 8% 1	4428
	11th to 20th	Night	46% 40% 7% 6% 1	4440
	21st to end	Night	41% 44% 12% 3	4884
February	1st to 10th	Night	23% 65% 4 5% 2	2608
	11th to 20th	Night	23% 65% 4 6% 2	2267
	21st to end	Night	21% 65% 4 7% 3	1884
March	1st to 10th	Night	24% 42% 17% 13% 4	3733
	11th to 20th	Night	35% 41% 7% 15% 4	3710
	21st to end	Night	38% 43% 7% 8% 4 1	3503
April	1st to 10th	Night	21% 66% 3 5% 4	1900
	11th to 20th	Night	18% 66% 3 8% 3 1	1833
	21st to end	Night	18% 65% 3 8% 6%	1710
May	1st to 10th	Night	23% 41% 6% 19% 10% 1	2685
	11th to 20th	Night	21% 43% 8% 19% 9%	2507
	21st to end	Night	32% 42% 7% 8% 8% 3	2751
June	1st to 10th	Night	16% 66% 4 9% 5%	1520
	11th to 20th	Night	19% 66% 3 8% 3 1	1437
	21st to end	Night	16% 64% 5% 9% 6%	1520
July	1st to 10th	Night	32% 39% 10% 11% 6% 2	2490
	11th to 20th	Night	15% 38% 9% 30% 7% 1	2482
	21st to end	Night	21% 37% 6% 17% 19% 1	2662
August	1st to 10th	Night	25% 39% 7% 19% 9%	2508
	11th to 20th	Night	26% 39% 10% 21% 5%	2740
	21st to end	Night	29% 39% 8% 14% 10% 1	3439
September	1st to 10th	Night	16% 61% 6% 12% 4	1900
	11th to 20th	Night	18% 62% 6% 11% 3	2009
	21st to end	Night	18% 61% 7% 11% 2 1	2090
October	1st to 10th	Night	21% 61% 6% 8% 4	2151
	11th to 20th	Night	21% 61% 6% 9% 3	2394
	21st to end	Night	26% 61% 5% 5% 2	2717
November	1st to 10th	Night	28% 60% 5% 6% 2	2433
	11th to 20th	Night	27% 61% 5% 5% 2	2512
	21st to end	Night	31% 61% 3 3 1	2660
December	1st to 10th	Night	27% 61% 6% 4 1	2838
	11th to 20th	Night	35% 51% 7% 5% 2	3490
	21st to end	Night	55% 39% 4 2 1	4884

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	19% 16% 39% 24% 3	270
	11th to 20th	Day	18% 15% 43% 20% 3 1	270
	21st to end	Day	17% 13% 44% 22% 4	297
February	1st to 10th	Day	21% 15% 41% 17% 5%	270
	11th to 20th	Day	14% 25% 44% 15% 3	270
	21st to end	Day	23% 22% 39% 15%	225
March	1st to 10th	Day	14% 24% 42% 15% 5%	270
	11th to 20th	Day	18% 21% 37% 19% 5% 1	320
	21st to end	Day	24% 20% 32% 17% 7%	506
April	1st to 10th	Day	25% 15% 35% 21% 4 1	460
	11th to 20th	Day	27% 17% 28% 21% 7% 1	452
	21st to end	Day	21% 18% 28% 23% 7% 2	460
May	1st to 10th	Day	18% 18% 35% 20% 7% 2	555
	11th to 20th	Day	18% 13% 38% 23% 5% 3	675
	21st to end	Day	15% 13% 35% 26% 8% 3	734
June	1st to 10th	Day	13% 15% 34% 27% 9% 3	680
	11th to 20th	Day	16% 13% 35% 26% 9% 2	680
	21st to end	Day	18% 8% 33% 28% 10% 3	680
July	1st to 10th	Day	8% 7% 32% 35% 12% 5%	671
	11th to 20th	Day	11% 9% 32% 32% 13% 3	668
	21st to end	Day	9% 8% 33% 32% 15% 5%	739
August	1st to 10th	Day	11% 9% 33% 32% 13% 3	676
	11th to 20th	Day	14% 9% 23% 28% 22% 5%	528
	21st to end	Day	19% 11% 27% 25% 13% 4	539
September	1st to 10th	Day	19% 11% 31% 23% 12% 4	490
	11th to 20th	Day	12% 11% 32% 30% 11% 2	490
	21st to end	Day	21% 13% 27% 26% 11% 1	490
October	1st to 10th	Day	26% 15% 29% 20% 8% 1	428
	11th to 20th	Day	27% 24% 36% 12% 2	300
	21st to end	Day	32% 22% 35% 10% 2	330
November	1st to 10th	Day	21% 22% 34% 20% 4	276
	11th to 20th	Day	21% 27% 39% 10% 3	270
	21st to end	Day	21% 27% 32% 17% 1	270
December	1st to 10th	Day	19% 17% 36% 21% 7% 1	183
	11th to 20th	Day	26% 24% 35% 11% 3 1	186
	21st to end	Day	24% 23% 38% 12% 2	297
January	1st to 10th	Night	17% 20% 42% 18% 3	950
	11th to 20th	Night	19% 19% 41% 17% 4 1	950
	21st to end	Night	17% 16% 38% 23% 5% 1	1045
February	1st to 10th	Night	16% 18% 39% 21% 6%	950
	11th to 20th	Night	16% 18% 38% 21% 6%	791
	21st to end	Night	19% 15% 43% 18% 4	628
March	1st to 10th	Night	14% 14% 37% 26% 8% 1	760
	11th to 20th	Night	17% 19% 35% 23% 6% 1	760
	21st to end	Night	21% 12% 32% 25% 8% 1	651
April	1st to 10th	Night	24% 14% 30% 25% 6% 1	570
	11th to 20th	Night	25% 12% 28% 26% 8% 1	563
	21st to end	Night	20% 10% 31% 28% 10% 1	570
May	1st to 10th	Night	19% 10% 25% 32% 11% 2	570
	11th to 20th	Night	19% 10% 27% 32% 10% 2	561
	21st to end	Night	16% 8% 29% 35% 13%	617
June	1st to 10th	Night	14% 7% 27% 37% 14% 1	570
	11th to 20th	Night	17% 7% 26% 37% 12%	487
	21st to end	Night	17% 7% 27% 34% 12% 3	570
July	1st to 10th	Night	12% 3 25% 37% 20% 3	555
	11th to 20th	Night	12% 4 31% 35% 17% 1	552
	21st to end	Night	9% 4 30% 36% 18% 4	624
August	1st to 10th	Night	11% 4 30% 35% 19% 1	567
	11th to 20th	Night	12% 3 21% 36% 26% 4	564
	21st to end	Night	15% 7% 29% 31% 17% 1	627
September	1st to 10th	Night	16% 5% 26% 31% 18% 3	570
	11th to 20th	Night	15% 8% 32% 33% 11%	679
	21st to end	Night	21% 8% 27% 32% 11% 1	760
October	1st to 10th	Night	22% 12% 33% 23% 9% 2	760
	11th to 20th	Night	23% 16% 35% 20% 6%	760
	21st to end	Night	30% 15% 32% 18% 5% 1	836
November	1st to 10th	Night	23% 16% 38% 20% 4	749
	11th to 20th	Night	23% 23% 34% 16% 4	802
	21st to end	Night	23% 19% 37% 18% 3	950
December	1st to 10th	Night	18% 22% 40% 15% 5% 1	950
	11th to 20th	Night	21% 18% 35% 19% 6% 2	950
	21st to end	Night	25% 19% 37% 17% 3	1045

Page generated at 2024-10-31 03:39:27. Version ac07

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