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 2024-03-01.

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	20% 11% 5% 8% 7% 4 5% 4 5% 6% 25%	78311
	Night	20% 11% 5% 9% 7% 3 5% 5% 5% 6% 25%	81134
Transparency	Day	59% 6% 12% 16% 7% 1	78014
	Night	59% 6% 12% 16% 6%	80966
Seeing	Day	27% 15% 31% 19% 7% 1	16659
	Night	26% 14% 30% 23% 6% 1	24184

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% 8% 17% 10% 5% 5% 4 5% 5% 16%	2526
	11th to 20th	Day	11% 11% 7% 15% 13% 5% 5% 5% 6% 7% 15%	2530
	21st to end	Day	14% 11% 8% 14% 9% 4 5% 4 5% 5% 21%	2814
February	1st to 10th	Day	17% 10% 6% 14% 9% 5% 6% 6% 6% 6% 15%	1710
	11th to 20th	Day	15% 14% 6% 10% 9% 5% 6% 5% 6% 7% 18%	1674
	21st to end	Day	9% 13% 7% 8% 9% 4 5% 4 5% 5% 30%	1570
March	1st to 10th	Day	13% 16% 6% 10% 7% 5% 5% 4 3 6% 26%	1796
	11th to 20th	Day	13% 11% 7% 9% 9% 4 6% 5% 5% 6% 24%	1946
	21st to end	Day	19% 16% 7% 7% 7% 4 4 4 4 5% 25%	2312
April	1st to 10th	Day	21% 13% 4 9% 6% 4 5% 4 5% 5% 24%	2160
	11th to 20th	Day	21% 11% 5% 5% 5% 3 3 4 4 6% 33%	2134
	21st to end	Day	25% 13% 3 6% 6% 2 4 4 5% 5% 26%	2320
May	1st to 10th	Day	27% 11% 3 5% 5% 3 4 4 5% 6% 27%	2520
	11th to 20th	Day	23% 11% 4 6% 5% 4 4 3 4 6% 31%	2478
	21st to end	Day	21% 9% 3 6% 5% 3 4 4 5% 8% 31%	2724
June	1st to 10th	Day	30% 10% 4 6% 5% 3 4 4 5% 7% 23%	2520
	11th to 20th	Day	20% 8% 3 6% 6% 3 4 4 5% 8% 33%	2520
	21st to end	Day	27% 10% 4 7% 7% 3 4 4 5% 6% 24%	2520
July	1st to 10th	Day	17% 7% 3 5% 6% 4 5% 5% 6% 9% 33%	2520
	11th to 20th	Day	17% 7% 3 5% 5% 4 6% 6% 6% 9% 31%	2520
	21st to end	Day	21% 8% 4 6% 6% 4 5% 4 7% 7% 27%	2745
August	1st to 10th	Day	19% 6% 2 6% 6% 4 6% 5% 6% 8% 32%	2506
	11th to 20th	Day	21% 7% 2 7% 5% 3 6% 5% 7% 7% 31%	2296
	21st to end	Day	18% 6% 3 5% 5% 4 5% 5% 6% 8% 33%	2376
September	1st to 10th	Day	19% 7% 2 6% 5% 3 5% 5% 4 8% 37%	2160
	11th to 20th	Day	21% 9% 3 5% 6% 3 5% 4 5% 6% 33%	2146
	21st to end	Day	19% 7% 2 5% 6% 3 4 4 5% 7% 38%	1944
October	1st to 10th	Day	20% 9% 2 6% 5% 3 5% 5% 6% 9% 31%	1800
	11th to 20th	Day	21% 10% 4 7% 7% 4 5% 5% 5% 7% 24%	1800
	21st to end	Day	25% 14% 5% 8% 7% 3 4 4 6% 6% 19%	1800
November	1st to 10th	Day	22% 14% 6% 7% 7% 4 5% 4 5% 5% 22%	1670
	11th to 20th	Day	21% 20% 5% 8% 8% 4 5% 5% 4 5% 15%	1525
	21st to end	Day	17% 19% 5% 9% 7% 4 5% 5% 6% 6% 16%	1520
December	1st to 10th	Day	22% 16% 8% 11% 7% 5% 6% 4 4 5% 12%	1520
	11th to 20th	Day	26% 20% 7% 12% 7% 4 4 4 4 4 8%	1906
	21st to end	Day	22% 18% 7% 11% 9% 3 4 5% 4 4 14%	2783
January	1st to 10th	Night	11% 13% 8% 16% 8% 4 6% 5% 5% 5% 19%	4429
	11th to 20th	Night	18% 10% 6% 18% 12% 4 6% 5% 5% 5% 11%	4440
	21st to end	Night	12% 12% 7% 15% 10% 4 6% 5% 5% 6% 18%	4850
February	1st to 10th	Night	17% 13% 4 12% 9% 4 6% 6% 5% 5% 18%	2470
	11th to 20th	Night	16% 11% 5% 10% 10% 5% 7% 5% 5% 6% 21%	2391
	21st to end	Night	10% 12% 6% 12% 10% 4 5% 5% 5% 6% 25%	1884
March	1st to 10th	Night	15% 13% 6% 9% 8% 4 5% 5% 4 5% 27%	2158
	11th to 20th	Night	16% 11% 5% 7% 8% 4 6% 5% 4 6% 30%	2011
	21st to end	Night	21% 13% 6% 7% 6% 3 5% 4 4 4 27%	2043
April	1st to 10th	Night	22% 10% 4 7% 6% 3 5% 4 4 6% 28%	1800
	11th to 20th	Night	21% 10% 4 7% 5% 3 3 5% 5% 6% 33%	1776
	21st to end	Night	25% 11% 3 6% 5% 3 4 3 4 5% 32%	1635
May	1st to 10th	Night	29% 10% 3 4 3 2 3 4 5% 6% 29%	1440
	11th to 20th	Night	22% 10% 3 5% 4 2 4 4 4 7% 37%	1416
	21st to end	Night	18% 8% 4 6% 5% 4 5% 5% 6% 9% 31%	1550
June	1st to 10th	Night	31% 10% 4 6% 5% 3 4 4 5% 5% 22%	1440
	11th to 20th	Night	23% 6% 3 6% 5% 2 5% 4 4 6% 35%	1440
	21st to end	Night	27% 8% 3 8% 5% 3 3 4 5% 7% 27%	1440
July	1st to 10th	Night	19% 7% 3 6% 5% 3 6% 6% 6% 8% 31%	1440
	11th to 20th	Night	17% 7% 4 6% 5% 3 5% 7% 6% 9% 30%	1440
	21st to end	Night	20% 8% 3 6% 6% 4 5% 4 7% 8% 29%	1573
August	1st to 10th	Night	18% 5% 3 5% 6% 4 6% 5% 6% 8% 34%	1433
	11th to 20th	Night	20% 7% 3 6% 6% 4 6% 6% 6% 7% 31%	1599
	21st to end	Night	16% 6% 2 5% 5% 4 5% 5% 6% 8% 39%	1980
September	1st to 10th	Night	16% 7% 3 5% 4 3 5% 5% 6% 8% 39%	1800
	11th to 20th	Night	22% 7% 2 6% 5% 2 4 4 5% 6% 38%	1813
	21st to end	Night	20% 7% 3 6% 5% 3 4 4 4 6% 37%	2011
October	1st to 10th	Night	18% 7% 2 6% 5% 3 5% 4 6% 8% 35%	2160
	11th to 20th	Night	23% 8% 3 5% 6% 3 5% 5% 5% 7% 31%	2160
	21st to end	Night	25% 12% 3 8% 7% 3 5% 5% 5% 5% 24%	2555
November	1st to 10th	Night	20% 12% 4 7% 7% 4 5% 5% 5% 6% 24%	2408
	11th to 20th	Night	23% 16% 5% 8% 7% 4 5% 5% 5% 6% 17%	2652
	21st to end	Night	21% 15% 5% 8% 7% 4 5% 6% 6% 6% 18%	2660
December	1st to 10th	Night	21% 17% 6% 9% 8% 4 5% 5% 5% 5% 14%	2660
	11th to 20th	Night	26% 18% 6% 11% 7% 3 4 4 4 4 13%	3293
	21st to end	Night	27% 16% 6% 13% 6% 3 4 3 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	55% 5% 11% 17% 10% 2	1570
March	1st to 10th	Day	60% 5% 7% 18% 9% 1	1800
	11th to 20th	Day	59% 5% 9% 18% 7% 1	1946
	21st to end	Day	64% 5% 7% 15% 8% 1	2312
April	1st to 10th	Day	61% 5% 9% 14% 8% 2	2160
	11th to 20th	Day	54% 4 9% 20% 11% 2	2134
	21st to end	Day	61% 5% 10% 15% 9% 1	2320
May	1st to 10th	Day	59% 5% 11% 15% 8% 2	2520
	11th to 20th	Day	56% 4 10% 20% 9% 1	2482
	21st to end	Day	53% 6% 13% 20% 8% 1	2724
June	1st to 10th	Day	63% 5% 10% 17% 5% 1	2520
	11th to 20th	Day	52% 6% 13% 20% 9% 1	2520
	21st to end	Day	61% 6% 10% 14% 8%	2520
July	1st to 10th	Day	46% 7% 18% 20% 8%	2450
	11th to 20th	Day	49% 7% 15% 20% 8%	2444
	21st to end	Day	56% 6% 14% 17% 6%	2592
August	1st to 10th	Day	48% 8% 16% 21% 6%	2492
	11th to 20th	Day	52% 7% 15% 20% 6%	2296
	21st to end	Day	48% 6% 16% 24% 7%	2376
September	1st to 10th	Day	47% 6% 14% 22% 9% 1	2160
	11th to 20th	Day	52% 4 10% 22% 9% 1	2146
	21st to end	Day	46% 6% 12% 25% 11% 1	1944
October	1st to 10th	Day	49% 7% 13% 22% 10%	1800
	11th to 20th	Day	59% 5% 12% 19% 5%	1800
	21st to end	Day	65% 6% 11% 13% 5%	1800
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	60% 5% 9% 17% 8% 1	2167
	11th to 20th	Night	55% 5% 12% 18% 9% 1	2012
	21st to end	Night	61% 5% 8% 15% 9% 2	2043
April	1st to 10th	Night	57% 4 10% 16% 11% 1	1800
	11th to 20th	Night	53% 5% 10% 19% 12% 2	1776
	21st to end	Night	57% 4 9% 18% 11% 1	1635
May	1st to 10th	Night	57% 5% 9% 19% 10% 1	1440
	11th to 20th	Night	50% 3 9% 23% 13% 2	1417
	21st to end	Night	49% 7% 15% 20% 8%	1551
June	1st to 10th	Night	64% 4 10% 16% 6% 1	1440
	11th to 20th	Night	50% 5% 13% 19% 13%	1440
	21st to end	Night	58% 7% 12% 16% 7% 1	1440
July	1st to 10th	Night	50% 7% 18% 19% 7%	1401
	11th to 20th	Night	50% 7% 15% 18% 9% 1	1392
	21st to end	Night	53% 7% 18% 17% 5% 1	1486
August	1st to 10th	Night	48% 7% 18% 22% 7%	1422
	11th to 20th	Night	50% 8% 17% 19% 6%	1599
	21st to end	Night	42% 7% 17% 25% 8%	1980
September	1st to 10th	Night	43% 8% 15% 24% 10%	1800
	11th to 20th	Night	48% 5% 11% 25% 11% 1	1813
	21st to end	Night	48% 6% 10% 25% 10%	2011
October	1st to 10th	Night	46% 6% 15% 22% 10% 1	2160
	11th to 20th	Night	50% 7% 16% 22% 4	2160
	21st to end	Night	63% 6% 9% 16% 6%	2555
November	1st to 10th	Night	59% 8% 13% 15% 5%	2408
	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% 23% 37% 17% 5% 1	307
March	1st to 10th	Day	23% 25% 30% 16% 4 1	340
	11th to 20th	Day	18% 24% 33% 16% 8% 1	406
	21st to end	Day	31% 22% 26% 14% 6% 2	462
April	1st to 10th	Day	32% 27% 27% 10% 4	420
	11th to 20th	Day	29% 19% 33% 14% 4	412
	21st to end	Day	33% 12% 31% 17% 6% 1	508
May	1st to 10th	Day	36% 14% 28% 15% 5% 2	603
	11th to 20th	Day	28% 12% 29% 19% 10% 2	624
	21st to end	Day	26% 14% 34% 20% 5% 1	680
June	1st to 10th	Day	39% 9% 24% 21% 7% 1	630
	11th to 20th	Day	25% 10% 34% 22% 7% 2	630
	21st to end	Day	32% 8% 30% 21% 9% 1	630
July	1st to 10th	Day	21% 8% 35% 25% 10% 1	620
	11th to 20th	Day	19% 7% 34% 28% 11% 1	618
	21st to end	Day	26% 5% 29% 30% 9% 1	685
August	1st to 10th	Day	20% 3 32% 32% 11% 2	625
	11th to 20th	Day	23% 6% 31% 25% 13% 2	460
	21st to end	Day	19% 9% 34% 25% 10% 3	495
September	1st to 10th	Day	21% 8% 38% 23% 8% 2	450
	11th to 20th	Day	33% 11% 30% 18% 7% 2	443
	21st to end	Day	24% 11% 35% 18% 11% 2	360
October	1st to 10th	Day	24% 11% 31% 21% 11% 3	360
	11th to 20th	Day	22% 14% 31% 19% 11% 3	360
	21st to end	Day	27% 23% 30% 14% 6% 1	396
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%	723
	11th to 20th	Night	23% 14% 32% 23% 8% 1	720
	21st to end	Night	27% 15% 31% 21% 5% 1	657
April	1st to 10th	Night	28% 18% 30% 21% 3	540
	11th to 20th	Night	27% 13% 31% 24% 5% 1	534
	21st to end	Night	33% 10% 29% 19% 8%	540
May	1st to 10th	Night	34% 10% 30% 17% 8% 2	540
	11th to 20th	Night	29% 6% 30% 25% 9% 1	532
	21st to end	Night	24% 10% 35% 23% 7% 1	583
June	1st to 10th	Night	35% 9% 26% 25% 5%	540
	11th to 20th	Night	26% 7% 32% 28% 7%	540
	21st to end	Night	29% 6% 30% 28% 6%	540
July	1st to 10th	Night	22% 6% 31% 31% 9% 1	526
	11th to 20th	Night	20% 5% 33% 34% 7%	522
	21st to end	Night	25% 4 27% 35% 9%	590
August	1st to 10th	Night	19% 6% 25% 37% 12% 1	538
	11th to 20th	Night	23% 3 23% 37% 12% 1	532
	21st to end	Night	18% 6% 23% 41% 12%	594
September	1st to 10th	Night	18% 6% 30% 34% 11% 1	540
	11th to 20th	Night	25% 11% 25% 28% 10% 1	540
	21st to end	Night	24% 9% 35% 25% 8%	571
October	1st to 10th	Night	23% 9% 31% 30% 8%	720
	11th to 20th	Night	26% 8% 30% 26% 9% 2	720
	21st to end	Night	31% 15% 30% 19% 5% 1	882
November	1st to 10th	Night	28% 15% 30% 21% 5% 1	830
	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 2024-02-27 07:30:17. Version ac07

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