Tecumseh
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tecumseh clear sky chart from 2005-11-06 to 2024-03-01.

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	11% 7% 3 6% 5% 3 4 4 5% 7% 45%	78509
	Night	11% 7% 3 5% 4 3 4 4 5% 6% 49%	80918
Transparency	Day	38% 5% 13% 25% 16% 3	78232
	Night	36% 5% 12% 26% 18% 3	80715
Seeing	Day	14% 10% 30% 28% 15% 3	14646
	Night	13% 9% 33% 33% 11% 1	24722

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% 10% 3 9% 6% 3 4 4 5% 6% 37%	2847
	11th to 20th	Day	9% 10% 5% 8% 7% 5% 6% 3 4 6% 37%	2850
	21st to end	Day	13% 14% 7% 7% 4 2 3 4 3 6% 36%	3135
February	1st to 10th	Day	13% 11% 4 7% 5% 4 3 4 4 5% 41%	1710
	11th to 20th	Day	10% 8% 5% 6% 5% 3 4 4 5% 7% 42%	1705
	21st to end	Day	9% 10% 3 6% 4 3 4 3 5% 7% 46%	1592
March	1st to 10th	Day	11% 8% 3 6% 6% 3 4 5% 4 7% 44%	1980
	11th to 20th	Day	20% 10% 3 6% 4 2 4 4 4 6% 39%	1980
	21st to end	Day	18% 11% 4 6% 6% 3 4 4 5% 6% 33%	2178
April	1st to 10th	Day	14% 6% 3 5% 5% 2 4 4 4 7% 47%	2038
	11th to 20th	Day	14% 7% 3 6% 5% 3 4 4 4 7% 42%	2148
	21st to end	Day	18% 7% 3 6% 5% 3 5% 4 4 6% 39%	2340
May	1st to 10th	Day	16% 9% 3 6% 5% 2 5% 5% 4 6% 38%	2340
	11th to 20th	Day	15% 6% 3 5% 5% 4 5% 5% 5% 8% 41%	2302
	21st to end	Day	15% 6% 3 6% 5% 3 5% 6% 7% 8% 35%	2531
June	1st to 10th	Day	5% 3 2 4 4 3 5% 6% 8% 11% 50%	2398
	11th to 20th	Day	7% 4 2 5% 5% 2 5% 5% 6% 10% 49%	2508
	21st to end	Day	6% 4 2 4 4 3 5% 5% 6% 8% 53%	2340
July	1st to 10th	Day	9% 5% 2 4 4 3 5% 6% 6% 9% 46%	2340
	11th to 20th	Day	3 2 2 4 4 3 5% 5% 8% 9% 54%	2340
	21st to end	Day	8% 5% 2 5% 5% 3 4 5% 7% 9% 48%	2546
August	1st to 10th	Day	7% 4 2 4 4 3 5% 7% 8% 10% 46%	2328
	11th to 20th	Day	7% 5% 2 5% 5% 3 4 4 5% 9% 51%	2301
	21st to end	Day	7% 5% 2 3 4 3 5% 4 5% 8% 54%	2476
September	1st to 10th	Day	12% 4 1 4 5% 3 4 3 5% 7% 53%	2106
	11th to 20th	Day	9% 4 2 5% 5% 4 5% 5% 5% 6% 49%	1980
	21st to end	Day	8% 4 1 4 4 2 4 5% 5% 7% 56%	1980
October	1st to 10th	Day	11% 6% 2 4 4 3 2 4 5% 8% 51%	1828
	11th to 20th	Day	12% 5% 2 4 4 2 3 3 4 5% 57%	1800
	21st to end	Day	16% 6% 2 5% 3 2 4 3 5% 5% 50%	1980
November	1st to 10th	Day	8% 5% 2 4 3 3 3 4 4 7% 56%	1797
	11th to 20th	Day	12% 5% 2 4 3 2 3 4 3 5% 56%	1710
	21st to end	Day	16% 6% 3 4 4 2 2 3 4 6% 50%	1552
December	1st to 10th	Day	10% 6% 3 4 5% 3 4 5% 5% 7% 48%	1520
	11th to 20th	Day	11% 9% 4 7% 6% 3 3 4 4 6% 42%	1918
	21st to end	Day	15% 15% 7% 12% 6% 3 4 4 4 6% 25%	3085
January	1st to 10th	Night	8% 9% 4 13% 7% 3 4 3 4 5% 40%	4108
	11th to 20th	Night	10% 9% 4 7% 5% 4 7% 4 4 5% 41%	4120
	21st to end	Night	16% 12% 4 7% 5% 3 4 4 3 5% 38%	4532
February	1st to 10th	Night	11% 11% 3 6% 6% 3 4 4 5% 6% 41%	2470
	11th to 20th	Night	11% 7% 3 7% 5% 2 5% 4 4 6% 46%	2380
	21st to end	Night	10% 7% 3 5% 5% 3 4 3 5% 5% 50%	1860
March	1st to 10th	Night	11% 7% 3 5% 5% 2 4 4 5% 6% 50%	1986
	11th to 20th	Night	15% 8% 3 4 4 2 5% 4 5% 6% 44%	1980
	21st to end	Night	21% 8% 3 5% 4 3 4 4 4 7% 36%	2178
April	1st to 10th	Night	10% 6% 2 5% 4 3 4 3 4 8% 52%	1922
	11th to 20th	Night	12% 7% 2 5% 5% 3 4 4 4 8% 45%	1758
	21st to end	Night	17% 6% 2 4 4 3 5% 5% 5% 5% 44%	1620
May	1st to 10th	Night	16% 6% 3 4 5% 3 5% 5% 6% 7% 40%	1620
	11th to 20th	Night	13% 5% 2 4 4 3 4 3 4 8% 49%	1593
	21st to end	Night	10% 5% 3 5% 6% 2 4 4 6% 9% 47%	1745
June	1st to 10th	Night	4 3 2 3 4 3 4 5% 6% 9% 57%	1548
	11th to 20th	Night	6% 3 2 3 4 2 5% 5% 7% 10% 53%	1440
	21st to end	Night	4 3 1 4 3 2 4 4 6% 9% 61%	1618
July	1st to 10th	Night	7% 3 2 3 5% 2 5% 4 7% 7% 55%	1620
	11th to 20th	Night	2 2 1 3 3 2 3 6% 8% 9% 61%	1620
	21st to end	Night	6% 4 2 4 5% 3 3 5% 6% 9% 52%	1772
August	1st to 10th	Night	4 1 1 4 5% 3 6% 6% 6% 11% 53%	1611
	11th to 20th	Night	5% 3 2 4 4 3 4 4 5% 8% 58%	1600
	21st to end	Night	6% 3 1 4 3 2 3 4 4 7% 62%	1880
September	1st to 10th	Night	11% 4 2 5% 4 2 3 4 5% 6% 55%	1851
	11th to 20th	Night	9% 4 1 4 4 3 4 5% 5% 7% 55%	1980
	21st to end	Night	6% 4 2 4 4 3 4 4 5% 6% 60%	1980
October	1st to 10th	Night	12% 4 2 4 4 3 3 4 4 6% 54%	2113
	11th to 20th	Night	13% 4 2 3 3 2 3 3 3 6% 58%	2160
	21st to end	Night	14% 7% 2 5% 4 2 3 3 3 4 54%	2376
November	1st to 10th	Night	8% 4 2 4 3 2 3 3 3 6% 62%	2280
	11th to 20th	Night	10% 4 2 3 4 2 4 4 4 6% 57%	2470
	21st to end	Night	13% 6% 2 3 3 2 3 3 4 5% 54%	2624
December	1st to 10th	Night	9% 7% 3 5% 5% 3 5% 5% 5% 6% 48%	2660
	11th to 20th	Night	11% 8% 3 6% 5% 3 3 5% 5% 6% 46%	3279
	21st to end	Night	18% 15% 5% 8% 5% 2 4 3 3 4 32%	4564

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	48% 5% 12% 24% 11% 1	2848
	11th to 20th	Day	50% 3 15% 19% 12% 1	2850
	21st to end	Day	50% 3 13% 20% 13% 1	3135
February	1st to 10th	Day	46% 5% 13% 22% 11% 3	1710
	11th to 20th	Day	42% 4 12% 25% 14% 3	1714
	21st to end	Day	39% 4 11% 24% 17% 5%	1592
March	1st to 10th	Day	40% 4 12% 23% 16% 4	1980
	11th to 20th	Day	48% 4 9% 22% 15% 2	1980
	21st to end	Day	52% 5% 15% 18% 8% 2	2178
April	1st to 10th	Day	38% 4 13% 23% 20% 2	2038
	11th to 20th	Day	43% 5% 13% 23% 16% 1	2148
	21st to end	Day	47% 5% 11% 25% 11% 1	2340
May	1st to 10th	Day	47% 6% 12% 20% 14% 1	2340
	11th to 20th	Day	41% 7% 15% 24% 13%	2306
	21st to end	Day	45% 9% 14% 22% 9% 2	2531
June	1st to 10th	Day	26% 9% 17% 30% 16% 2	2398
	11th to 20th	Day	31% 7% 13% 29% 18% 2	2508
	21st to end	Day	28% 6% 14% 31% 17% 4	2340
July	1st to 10th	Day	33% 8% 14% 26% 16% 4	2276
	11th to 20th	Day	24% 8% 16% 27% 20% 5%	2271
	21st to end	Day	29% 7% 14% 32% 16% 1	2405
August	1st to 10th	Day	30% 11% 16% 27% 15% 2	2314
	11th to 20th	Day	31% 6% 10% 33% 18% 2	2301
	21st to end	Day	28% 6% 12% 26% 21% 7%	2476
September	1st to 10th	Day	32% 5% 13% 26% 18% 7%	2106
	11th to 20th	Day	34% 6% 10% 26% 21% 3	1980
	21st to end	Day	28% 6% 10% 28% 25% 3	1980
October	1st to 10th	Day	32% 5% 12% 27% 21% 3	1828
	11th to 20th	Day	31% 3 8% 25% 27% 6%	1800
	21st to end	Day	36% 4 11% 24% 19% 6%	1980
November	1st to 10th	Day	29% 5% 12% 29% 20% 6%	1797
	11th to 20th	Day	32% 3 10% 29% 23% 3	1710
	21st to end	Day	37% 4 10% 26% 22% 2	1552
December	1st to 10th	Day	35% 4 15% 31% 14% 1	1520
	11th to 20th	Day	44% 4 12% 25% 13% 1	1915
	21st to end	Day	61% 4 10% 17% 8% 1	3085
January	1st to 10th	Night	47% 4 14% 22% 12% 1	4108
	11th to 20th	Night	46% 4 13% 22% 15% 1	4120
	21st to end	Night	49% 4 15% 19% 12% 2	4532
February	1st to 10th	Night	44% 5% 12% 22% 14% 3	2470
	11th to 20th	Night	40% 3 11% 25% 16% 4	2381
	21st to end	Night	37% 4 9% 22% 20% 7%	1860
March	1st to 10th	Night	36% 4 9% 26% 20% 5%	1986
	11th to 20th	Night	40% 6% 12% 23% 15% 4	1980
	21st to end	Night	49% 6% 12% 19% 11% 2	2178
April	1st to 10th	Night	34% 3 11% 25% 23% 4	1922
	11th to 20th	Night	38% 6% 9% 26% 18% 3	1758
	21st to end	Night	41% 6% 11% 26% 15% 1	1620
May	1st to 10th	Night	43% 7% 12% 21% 16% 2	1620
	11th to 20th	Night	35% 5% 15% 25% 18% 1	1594
	21st to end	Night	34% 7% 20% 25% 12% 2	1746
June	1st to 10th	Night	23% 7% 18% 34% 16% 3	1548
	11th to 20th	Night	25% 8% 13% 32% 18% 3	1440
	21st to end	Night	20% 5% 15% 34% 21% 4	1618
July	1st to 10th	Night	26% 7% 16% 29% 18% 4	1575
	11th to 20th	Night	16% 8% 16% 33% 24% 5%	1566
	21st to end	Night	27% 6% 11% 33% 21% 1	1673
August	1st to 10th	Night	23% 8% 18% 35% 14% 3	1601
	11th to 20th	Night	25% 5% 12% 33% 22% 3	1600
	21st to end	Night	23% 6% 11% 30% 24% 7%	1880
September	1st to 10th	Night	30% 5% 10% 28% 19% 8%	1851
	11th to 20th	Night	27% 6% 10% 27% 25% 5%	1980
	21st to end	Night	26% 4 9% 26% 31% 4	1980
October	1st to 10th	Night	32% 5% 9% 24% 25% 5%	2113
	11th to 20th	Night	30% 3 7% 28% 24% 9%	2160
	21st to end	Night	36% 3 9% 23% 26% 4	2376
November	1st to 10th	Night	26% 3 12% 28% 24% 7%	2280
	11th to 20th	Night	29% 4 11% 28% 24% 4	2470
	21st to end	Night	34% 3 10% 30% 20% 3	2624
December	1st to 10th	Night	36% 5% 13% 27% 17% 1	2660
	11th to 20th	Night	39% 4 10% 30% 16% 1	3281
	21st to end	Night	56% 4 8% 21% 8% 2	4564

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% 16% 36% 21% 7%	270
	11th to 20th	Day	25% 18% 39% 16% 2	270
	21st to end	Day	12% 15% 49% 21% 3	297
February	1st to 10th	Day	21% 20% 39% 17% 2	270
	11th to 20th	Day	18% 19% 46% 11% 6%	270
	21st to end	Day	12% 30% 41% 12% 4	225
March	1st to 10th	Day	14% 17% 45% 21% 3	240
	11th to 20th	Day	27% 14% 35% 18% 5%	240
	21st to end	Day	28% 21% 38% 11% 2	264
April	1st to 10th	Day	20% 18% 36% 19% 6%	298
	11th to 20th	Day	18% 15% 38% 23% 5% 1	426
	21st to end	Day	22% 15% 36% 17% 9% 1	600
May	1st to 10th	Day	18% 16% 36% 21% 8%	603
	11th to 20th	Day	19% 8% 32% 28% 11% 2	625
	21st to end	Day	18% 9% 30% 25% 15% 3	679
June	1st to 10th	Day	5% 5% 22% 36% 27% 6%	630
	11th to 20th	Day	6% 5% 29% 37% 18% 5%	630
	21st to end	Day	7% 6% 33% 38% 14% 2	630
July	1st to 10th	Day	10% 3 15% 35% 29% 9%	621
	11th to 20th	Day	4 3 18% 40% 29% 7%	618
	21st to end	Day	8% 2 19% 36% 28% 7%	684
August	1st to 10th	Day	8% 2 17% 41% 28% 4	626
	11th to 20th	Day	8% 2 19% 41% 25% 5%	615
	21st to end	Day	10% 1 14% 36% 31% 7%	595
September	1st to 10th	Day	14% 2 20% 35% 25% 4	396
	11th to 20th	Day	6% 3 23% 39% 25% 4	270
	21st to end	Day	14% 6% 30% 34% 13% 3	270
October	1st to 10th	Day	14% 8% 30% 28% 14% 6%	270
	11th to 20th	Day	10% 18% 44% 20% 7% 1	270
	21st to end	Day	23% 16% 34% 19% 8% 1	297
November	1st to 10th	Day	14% 13% 36% 27% 9% 2	270
	11th to 20th	Day	15% 18% 36% 24% 7%	270
	21st to end	Day	22% 14% 37% 19% 7%	270
December	1st to 10th	Day	9% 17% 39% 27% 6% 2	270
	11th to 20th	Day	17% 17% 37% 21% 7% 1	270
	21st to end	Day	21% 22% 38% 18% 1	297
January	1st to 10th	Night	12% 13% 38% 30% 7%	950
	11th to 20th	Night	15% 13% 38% 28% 5% 1	950
	21st to end	Night	14% 12% 40% 29% 4	1045
February	1st to 10th	Night	18% 13% 40% 26% 3	950
	11th to 20th	Night	15% 14% 40% 28% 3	906
	21st to end	Night	15% 14% 42% 23% 6%	604
March	1st to 10th	Night	14% 13% 42% 25% 5%	542
	11th to 20th	Night	19% 12% 35% 28% 5% 1	540
	21st to end	Night	24% 13% 36% 22% 4	594
April	1st to 10th	Night	14% 11% 43% 26% 6%	540
	11th to 20th	Night	16% 13% 41% 25% 5%	533
	21st to end	Night	20% 11% 37% 24% 6% 1	540
May	1st to 10th	Night	17% 9% 36% 30% 6% 1	540
	11th to 20th	Night	14% 9% 33% 33% 11% 1	531
	21st to end	Night	12% 6% 33% 33% 14% 2	584
June	1st to 10th	Night	5% 3 24% 42% 24% 1	540
	11th to 20th	Night	7% 3 29% 43% 17% 1	540
	21st to end	Night	4 4 33% 46% 12% 1	540
July	1st to 10th	Night	7% 3 13% 47% 28% 2	525
	11th to 20th	Night	3 1 18% 50% 26% 2	522
	21st to end	Night	7% 2 16% 48% 26% 1	591
August	1st to 10th	Night	4 1 18% 47% 28% 2	537
	11th to 20th	Night	6% 1 14% 49% 27% 2	534
	21st to end	Night	6% 2 17% 42% 31% 2	594
September	1st to 10th	Night	13% 3 19% 43% 20% 2	540
	11th to 20th	Night	10% 1 23% 42% 21% 2	540
	21st to end	Night	7% 4 28% 43% 17% 1	540
October	1st to 10th	Night	14% 5% 29% 33% 18% 1	673
	11th to 20th	Night	15% 8% 41% 28% 7%	720
	21st to end	Night	18% 12% 35% 27% 8%	792
November	1st to 10th	Night	10% 10% 34% 34% 11% 1	800
	11th to 20th	Night	12% 14% 38% 29% 7%	950
	21st to end	Night	17% 10% 35% 31% 7%	950
December	1st to 10th	Night	13% 12% 38% 31% 5% 1	950
	11th to 20th	Night	17% 10% 40% 28% 5%	950
	21st to end	Night	18% 15% 36% 26% 4	1045

Page generated at 2024-02-27 05:30:18. Version ac07

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