Leitches Creek
Clear Sky Chart
History

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

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	19% 12% 4 9% 6% 5% 5% 4 5% 6% 26%	101596
	Night	20% 12% 4 10% 6% 5% 5% 4 5% 6% 25%	97487
Transparency	Day	58% 6% 12% 17% 6% 1	101354
	Night	59% 6% 12% 16% 6%	97349
Seeing	Day	27% 15% 31% 19% 7% 1	17694
	Night	26% 14% 31% 23% 6% 1	24985

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	13% 13% 7% 19% 8% 7% 5% 3 5% 5% 16%	2526
	11th to 20th	Day	11% 12% 6% 19% 9% 6% 6% 4 6% 7% 15%	2530
	21st to end	Day	14% 12% 8% 15% 7% 6% 5% 3 5% 5% 21%	2814
February	1st to 10th	Day	17% 11% 5% 15% 8% 6% 6% 5% 6% 6% 15%	1710
	11th to 20th	Day	15% 14% 6% 11% 8% 6% 6% 4 6% 7% 18%	1674
	21st to end	Day	9% 15% 5% 10% 9% 5% 5% 3 5% 4 30%	1570
March	1st to 10th	Day	20% 13% 4 9% 6% 6% 4 2 3 4 28%	3114
	11th to 20th	Day	13% 19% 7% 12% 8% 6% 5% 4 5% 5% 17%	3432
	21st to end	Day	25% 18% 7% 10% 6% 4 3 3 3 4 16%	4061
April	1st to 10th	Day	21% 14% 4 9% 6% 5% 4 3 5% 5% 24%	2280
	11th to 20th	Day	21% 12% 4 7% 4 3 3 3 5% 5% 33%	2254
	21st to end	Day	24% 14% 3 7% 5% 3 4 3 5% 5% 28%	2450
May	1st to 10th	Day	28% 16% 3 7% 4 3 3 3 4 5% 24%	4425
	11th to 20th	Day	21% 12% 3 7% 4 4 4 3 5% 6% 30%	4398
	21st to end	Day	20% 10% 3 7% 4 5% 5% 4 6% 8% 29%	4836
June	1st to 10th	Day	30% 11% 3 7% 4 4 3 3 5% 7% 22%	2660
	11th to 20th	Day	19% 9% 3 7% 5% 4 4 3 5% 8% 33%	2660
	21st to end	Day	26% 11% 3 8% 6% 3 3 3 6% 6% 23%	2660
July	1st to 10th	Day	20% 9% 3 7% 6% 5% 5% 4 5% 8% 28%	4440
	11th to 20th	Day	15% 6% 3 8% 5% 5% 6% 5% 7% 9% 30%	4440
	21st to end	Day	15% 7% 3 6% 5% 5% 5% 4 7% 8% 36%	4815
August	1st to 10th	Day	17% 9% 3 8% 6% 5% 7% 5% 7% 8% 26%	4424
	11th to 20th	Day	21% 7% 3 8% 5% 5% 4 4 7% 8% 28%	4022
	21st to end	Day	13% 6% 3 7% 4 4 5% 4 6% 7% 40%	4180
September	1st to 10th	Day	19% 8% 2 6% 5% 4 5% 3 5% 8% 36%	2280
	11th to 20th	Day	20% 9% 3 6% 5% 4 5% 3 5% 6% 34%	2265
	21st to end	Day	19% 7% 2 7% 5% 4 4 3 5% 6% 37%	2052
October	1st to 10th	Day	20% 9% 3 7% 4 4 4 4 6% 8% 30%	1900
	11th to 20th	Day	20% 11% 4 9% 6% 5% 5% 4 6% 7% 25%	1900
	21st to end	Day	24% 15% 4 10% 5% 4 4 3 5% 6% 20%	1900
November	1st to 10th	Day	22% 15% 4 8% 6% 5% 5% 3 5% 5% 22%	1670
	11th to 20th	Day	20% 21% 4 10% 6% 5% 5% 4 4 5% 15%	1525
	21st to end	Day	17% 19% 4 10% 6% 5% 6% 4 7% 6% 16%	1520
December	1st to 10th	Day	21% 18% 7% 12% 6% 6% 5% 3 4 5% 12%	1520
	11th to 20th	Day	25% 21% 7% 13% 7% 4 3 4 4 3 8%	1906
	21st to end	Day	22% 19% 6% 13% 7% 4 4 3 4 4 14%	2783
January	1st to 10th	Night	11% 13% 7% 18% 7% 6% 5% 4 5% 5% 19%	4429
	11th to 20th	Night	18% 12% 5% 20% 9% 6% 5% 4 5% 4 11%	4440
	21st to end	Night	12% 13% 7% 17% 8% 6% 5% 4 5% 6% 18%	4850
February	1st to 10th	Night	17% 13% 4 14% 7% 6% 6% 4 6% 5% 18%	2470
	11th to 20th	Night	16% 12% 5% 12% 8% 7% 6% 4 5% 5% 21%	2391
	21st to end	Night	10% 14% 5% 14% 9% 5% 5% 3 5% 6% 25%	1884
March	1st to 10th	Night	20% 12% 4 9% 6% 5% 4 4 4 5% 27%	3726
	11th to 20th	Night	19% 19% 5% 10% 6% 5% 4 3 3 5% 21%	3525
	21st to end	Night	26% 15% 6% 10% 5% 5% 5% 3 3 3 20%	3570
April	1st to 10th	Night	22% 12% 3 8% 6% 4 4 3 3 6% 27%	1900
	11th to 20th	Night	20% 11% 3 8% 4 4 3 3 5% 6% 33%	1876
	21st to end	Night	24% 11% 3 7% 4 4 3 3 3 4 32%	1725
May	1st to 10th	Night	28% 13% 3 6% 4 4 3 3 5% 6% 26%	2525
	11th to 20th	Night	19% 11% 3 7% 4 4 4 4 5% 6% 33%	2506
	21st to end	Night	18% 10% 3 7% 5% 5% 4 4 6% 9% 29%	2749
June	1st to 10th	Night	32% 11% 4 7% 4 3 4 3 5% 5% 22%	1520
	11th to 20th	Night	22% 7% 3 6% 4 3 4 3 5% 6% 36%	1520
	21st to end	Night	27% 9% 3 8% 5% 3 4 3 5% 7% 26%	1520
July	1st to 10th	Night	19% 9% 4 9% 5% 5% 6% 5% 5% 7% 26%	2530
	11th to 20th	Night	15% 9% 4 9% 5% 4 5% 5% 7% 8% 30%	2530
	21st to end	Night	16% 9% 3 7% 5% 4 4 3 6% 7% 36%	2750
August	1st to 10th	Night	15% 8% 4 9% 6% 5% 5% 4 6% 8% 29%	2516
	11th to 20th	Night	17% 8% 3 8% 5% 5% 5% 4 6% 8% 31%	2801
	21st to end	Night	15% 6% 2 5% 4 3 4 3 5% 8% 44%	3476
September	1st to 10th	Night	16% 7% 2 6% 4 4 4 4 5% 8% 40%	1900
	11th to 20th	Night	21% 7% 2 6% 4 3 4 4 5% 6% 39%	1914
	21st to end	Night	20% 8% 3 7% 5% 4 4 3 4 6% 37%	2123
October	1st to 10th	Night	19% 7% 2 8% 5% 4 5% 3 6% 8% 34%	2280
	11th to 20th	Night	22% 9% 3 6% 5% 4 4 4 5% 7% 31%	2280
	21st to end	Night	24% 12% 3 9% 5% 5% 4 4 5% 5% 24%	2697
November	1st to 10th	Night	20% 13% 4 8% 6% 6% 5% 4 5% 6% 24%	2415
	11th to 20th	Night	22% 17% 4 9% 6% 5% 5% 4 5% 6% 17%	2652
	21st to end	Night	21% 15% 4 9% 5% 5% 6% 4 6% 6% 18%	2660
December	1st to 10th	Night	21% 19% 5% 11% 6% 5% 5% 4 5% 5% 14%	2660
	11th to 20th	Night	25% 19% 6% 12% 5% 4 4 3 4 4 13%	3293
	21st to end	Night	27% 17% 6% 13% 5% 4 4 2 3 4 15%	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	66% 9% 12% 10% 2	2527
	11th to 20th	Day	66% 5% 12% 14% 3	2530
	21st to end	Day	62% 7% 11% 10% 9% 1	2814
February	1st to 10th	Day	67% 6% 9% 12% 6%	1710
	11th to 20th	Day	62% 7% 11% 13% 5% 1	1682
	21st to end	Day	56% 5% 11% 17% 10% 2	1570
March	1st to 10th	Day	60% 4 7% 20% 9% 1	3118
	11th to 20th	Day	68% 6% 8% 13% 5% 1	3432
	21st to end	Day	73% 4 7% 10% 5% 1	4061
April	1st to 10th	Day	61% 5% 9% 14% 8% 2	2280
	11th to 20th	Day	54% 4 10% 20% 11% 2	2254
	21st to end	Day	59% 5% 10% 15% 11% 1	2450
May	1st to 10th	Day	64% 5% 11% 14% 5% 1	4440
	11th to 20th	Day	56% 4 15% 19% 6%	4402
	21st to end	Day	52% 7% 16% 18% 6% 1	4836
June	1st to 10th	Day	63% 5% 10% 16% 5%	2660
	11th to 20th	Day	51% 6% 14% 20% 9% 1	2660
	21st to end	Day	62% 6% 10% 14% 7%	2660
July	1st to 10th	Day	54% 7% 15% 15% 9%	4370
	11th to 20th	Day	48% 9% 18% 19% 6%	4364
	21st to end	Day	45% 7% 19% 23% 6%	4662
August	1st to 10th	Day	54% 9% 14% 18% 5%	4410
	11th to 20th	Day	51% 7% 14% 23% 4	4062
	21st to end	Day	41% 6% 13% 28% 11%	4180
September	1st to 10th	Day	47% 6% 13% 23% 10% 1	2280
	11th to 20th	Day	51% 5% 12% 23% 9% 1	2265
	21st to end	Day	47% 6% 12% 25% 10% 1	2052
October	1st to 10th	Day	50% 6% 13% 21% 10%	1900
	11th to 20th	Day	57% 5% 11% 20% 6%	1900
	21st to end	Day	64% 6% 11% 14% 5%	1900
November	1st to 10th	Day	64% 6% 10% 16% 4	1670
	11th to 20th	Day	69% 6% 10% 11% 4	1525
	21st to end	Day	66% 7% 12% 11% 4	1520
December	1st to 10th	Day	73% 7% 9% 9% 3	1520
	11th to 20th	Day	79% 5% 6% 8% 2	1905
	21st to end	Day	72% 6% 13% 7% 2	2783
January	1st to 10th	Night	63% 8% 16% 11% 2	4429
	11th to 20th	Night	72% 6% 10% 9% 3	4440
	21st to end	Night	61% 9% 11% 12% 7%	4850
February	1st to 10th	Night	64% 6% 10% 12% 7% 1	2470
	11th to 20th	Night	63% 5% 11% 15% 5% 1	2394
	21st to end	Night	59% 6% 10% 15% 10% 2	1884
March	1st to 10th	Night	59% 4 8% 19% 9% 1	3735
	11th to 20th	Night	66% 4 9% 14% 6%	3526
	21st to end	Night	70% 3 6% 14% 6% 2	3570
April	1st to 10th	Night	58% 5% 9% 16% 11% 1	1900
	11th to 20th	Night	53% 5% 10% 19% 11% 1	1876
	21st to end	Night	57% 4 8% 18% 12% 2	1725
May	1st to 10th	Night	59% 6% 14% 14% 6% 1	2530
	11th to 20th	Night	52% 4 15% 21% 8% 1	2507
	21st to end	Night	51% 8% 15% 20% 6%	2750
June	1st to 10th	Night	65% 4 9% 16% 6% 1	1520
	11th to 20th	Night	49% 5% 13% 20% 13%	1520
	21st to end	Night	59% 6% 11% 16% 7% 1	1520
July	1st to 10th	Night	55% 6% 15% 16% 8%	2491
	11th to 20th	Night	50% 8% 17% 16% 9% 1	2482
	21st to end	Night	47% 7% 16% 22% 8%	2663
August	1st to 10th	Night	52% 7% 17% 20% 4	2505
	11th to 20th	Night	48% 9% 20% 19% 4	2827
	21st to end	Night	39% 6% 15% 32% 8%	3475
September	1st to 10th	Night	43% 8% 14% 24% 11%	1900
	11th to 20th	Night	46% 5% 12% 26% 10% 1	1914
	21st to end	Night	49% 6% 10% 25% 9%	2123
October	1st to 10th	Night	47% 6% 15% 21% 10%	2280
	11th to 20th	Night	50% 7% 16% 23% 5%	2280
	21st to end	Night	62% 6% 10% 16% 7%	2697
November	1st to 10th	Night	59% 8% 13% 15% 5%	2415
	11th to 20th	Night	64% 8% 12% 11% 4	2652
	21st to end	Night	63% 9% 13% 11% 4	2660
December	1st to 10th	Night	68% 8% 11% 10% 2	2660
	11th to 20th	Night	73% 6% 8% 10% 3	3295
	21st to end	Night	72% 5% 13% 8% 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	27% 23% 34% 14% 3	370
	11th to 20th	Day	30% 18% 34% 14% 4 1	370
	21st to end	Day	22% 20% 39% 15% 3	407
February	1st to 10th	Day	28% 25% 29% 15% 3	370
	11th to 20th	Day	27% 29% 24% 17% 2 1	366
	21st to end	Day	16% 24% 37% 17% 5% 1	307
March	1st to 10th	Day	24% 25% 29% 15% 5% 1	370
	11th to 20th	Day	19% 25% 32% 15% 8% 1	445
	21st to end	Day	33% 23% 25% 13% 5% 1	506
April	1st to 10th	Day	33% 26% 27% 10% 4	460
	11th to 20th	Day	29% 19% 33% 14% 4	452
	21st to end	Day	32% 14% 31% 16% 5% 1	553
May	1st to 10th	Day	38% 14% 27% 15% 5% 2	653
	11th to 20th	Day	27% 11% 30% 19% 10% 2	674
	21st to end	Day	25% 14% 36% 20% 5% 1	735
June	1st to 10th	Day	39% 10% 24% 20% 6% 1	680
	11th to 20th	Day	24% 11% 35% 21% 7% 1	680
	21st to end	Day	32% 9% 29% 20% 8% 1	680
July	1st to 10th	Day	22% 9% 34% 25% 9% 1	670
	11th to 20th	Day	19% 7% 35% 28% 10% 1	668
	21st to end	Day	24% 5% 30% 30% 9% 1	740
August	1st to 10th	Day	20% 4 34% 30% 10% 2	675
	11th to 20th	Day	23% 7% 32% 24% 12% 2	501
	21st to end	Day	19% 9% 34% 24% 10% 3	539
September	1st to 10th	Day	21% 10% 37% 23% 7% 2	490
	11th to 20th	Day	30% 10% 31% 20% 7% 2	482
	21st to end	Day	24% 11% 35% 18% 11% 2	390
October	1st to 10th	Day	25% 11% 31% 21% 11% 3	390
	11th to 20th	Day	22% 15% 32% 18% 10% 3	390
	21st to end	Day	27% 23% 30% 14% 6% 1	429
November	1st to 10th	Day	28% 19% 27% 17% 6% 2	365
	11th to 20th	Day	32% 20% 27% 16% 4 1	370
	21st to end	Day	31% 22% 28% 15% 4	370
December	1st to 10th	Day	32% 21% 30% 13% 3 1	370
	11th to 20th	Day	36% 21% 27% 13% 3	370
	21st to end	Day	25% 26% 30% 14% 5% 1	407
January	1st to 10th	Night	24% 22% 32% 19% 4	850
	11th to 20th	Night	26% 22% 31% 17% 4	850
	21st to end	Night	21% 20% 35% 19% 5%	924
February	1st to 10th	Night	28% 14% 33% 21% 4	760
	11th to 20th	Night	24% 26% 32% 15% 3	743
	21st to end	Night	17% 19% 36% 19% 8%	628
March	1st to 10th	Night	25% 16% 33% 20% 5%	760
	11th to 20th	Night	23% 14% 33% 22% 7% 1	760
	21st to end	Night	28% 15% 31% 20% 5% 1	693
April	1st to 10th	Night	28% 18% 30% 21% 3	570
	11th to 20th	Night	26% 14% 30% 24% 5% 1	564
	21st to end	Night	33% 11% 30% 19% 8%	570
May	1st to 10th	Night	34% 10% 29% 17% 8% 2	570
	11th to 20th	Night	28% 7% 29% 25% 10% 1	562
	21st to end	Night	24% 10% 36% 23% 6%	616
June	1st to 10th	Night	36% 9% 26% 25% 5%	570
	11th to 20th	Night	25% 7% 33% 28% 7%	570
	21st to end	Night	29% 6% 31% 27% 6%	570
July	1st to 10th	Night	22% 6% 31% 31% 9% 1	556
	11th to 20th	Night	20% 6% 33% 34% 7%	552
	21st to end	Night	24% 5% 27% 35% 8%	623
August	1st to 10th	Night	18% 6% 26% 37% 12% 1	568
	11th to 20th	Night	22% 4 24% 36% 12% 1	562
	21st to end	Night	18% 6% 23% 41% 12%	627
September	1st to 10th	Night	19% 7% 30% 33% 10% 1	570
	11th to 20th	Night	24% 11% 25% 29% 10% 1	570
	21st to end	Night	24% 9% 34% 25% 8%	603
October	1st to 10th	Night	23% 9% 30% 29% 9%	760
	11th to 20th	Night	26% 9% 30% 25% 9% 2	760
	21st to end	Night	30% 15% 31% 18% 5% 1	936
November	1st to 10th	Night	28% 15% 30% 21% 5% 1	833
	11th to 20th	Night	31% 17% 30% 15% 5% 1	850
	21st to end	Night	30% 18% 30% 18% 4	850
December	1st to 10th	Night	31% 19% 29% 16% 5%	850
	11th to 20th	Night	34% 20% 29% 13% 3	850
	21st to end	Night	27% 21% 32% 16% 2 1	935

Page generated at 2024-10-29 12:20:51. Version ac07

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