Springwater Conservation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Springwater Conservation Area clear sky chart from 2005-11-06 to 2026-06-16.

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	14% 10% 4 9% 5% 5% 5% 4 6% 7% 32%	138286
	Night	15% 10% 4 9% 5% 5% 5% 4 5% 7% 33%	133702
Transparency	Day	47% 9% 14% 19% 10% 1	141886
	Night	48% 8% 13% 18% 11% 1	138192
Seeing	Day	17% 11% 28% 26% 14% 4	16952
	Night	19% 10% 29% 29% 13% 2	26124

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	16% 15% 5% 18% 6% 5% 4 3 3 4 20%	5039
	11th to 20th	Day	10% 22% 9% 19% 10% 7% 4 2 4 5% 7%	5246
	21st to end	Day	16% 17% 6% 14% 7% 5% 5% 3 4 5% 18%	5780
February	1st to 10th	Day	16% 16% 5% 11% 8% 6% 5% 3 5% 5% 20%	1890
	11th to 20th	Day	15% 13% 7% 13% 7% 6% 5% 3 4 6% 21%	1843
	21st to end	Day	17% 14% 4 11% 7% 6% 6% 4 6% 5% 22%	1720
March	1st to 10th	Day	18% 11% 6% 12% 6% 4 4 3 5% 5% 26%	4947
	11th to 20th	Day	12% 11% 5% 10% 5% 5% 4 3 5% 8% 32%	5090
	21st to end	Day	19% 11% 4 10% 6% 5% 4 3 4 5% 29%	5586
April	1st to 10th	Day	17% 12% 4 8% 6% 4 4 3 6% 7% 29%	2394
	11th to 20th	Day	17% 11% 3 8% 5% 4 4 3 6% 7% 32%	2662
	21st to end	Day	19% 9% 3 8% 4 5% 4 3 5% 6% 35%	2730
May	1st to 10th	Day	19% 9% 3 8% 5% 4 5% 4 5% 7% 31%	7642
	11th to 20th	Day	15% 9% 3 7% 5% 4 5% 4 6% 8% 35%	7626
	21st to end	Day	15% 6% 2 6% 4 4 4 3 5% 8% 42%	9060
June	1st to 10th	Day	12% 5% 3 6% 5% 5% 4 5% 6% 8% 41%	2940
	11th to 20th	Day	10% 6% 2 7% 4 4 6% 5% 7% 9% 40%	2972
	21st to end	Day	11% 5% 2 6% 4 4 4 5% 6% 10% 42%	3000
July	1st to 10th	Day	8% 6% 2 6% 4 4 5% 5% 7% 10% 43%	6773
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 7% 8% 45%	5910
	21st to end	Day	8% 4 2 5% 4 4 5% 4 6% 9% 47%	6424
August	1st to 10th	Day	15% 5% 2 5% 4 4 5% 5% 7% 8% 40%	4234
	11th to 20th	Day	10% 7% 2 8% 4 5% 6% 5% 8% 10% 36%	4174
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 5% 6% 8% 43%	4587
September	1st to 10th	Day	10% 5% 2 7% 4 5% 5% 4 6% 9% 44%	2356
	11th to 20th	Day	9% 5% 2 5% 5% 4 4 4 6% 8% 49%	2200
	21st to end	Day	17% 7% 2 6% 4 4 6% 3 7% 7% 37%	2200
October	1st to 10th	Day	15% 6% 2 7% 4 4 4 4 6% 7% 40%	2033
	11th to 20th	Day	17% 9% 3 7% 5% 5% 5% 4 5% 8% 32%	2000
	21st to end	Day	22% 10% 3 9% 5% 5% 5% 4 4 6% 26%	2185
November	1st to 10th	Day	15% 8% 3 7% 6% 5% 5% 5% 6% 7% 34%	1852
	11th to 20th	Day	16% 12% 4 7% 4 5% 4 4 5% 8% 31%	1717
	21st to end	Day	19% 15% 6% 9% 6% 5% 6% 4 6% 6% 19%	1680
December	1st to 10th	Day	18% 16% 5% 10% 6% 5% 5% 4 6% 7% 17%	2680
	11th to 20th	Day	21% 18% 6% 9% 6% 4 4 3 5% 5% 18%	3066
	21st to end	Day	27% 20% 5% 12% 5% 5% 5% 3 4 5% 10%	4048
January	1st to 10th	Night	15% 14% 5% 15% 7% 6% 5% 4 5% 6% 19%	7837
	11th to 20th	Night	11% 18% 7% 16% 9% 7% 5% 4 4 5% 14%	7639
	21st to end	Night	16% 14% 7% 13% 6% 5% 5% 3 4 5% 21%	8401
February	1st to 10th	Night	16% 15% 4 10% 7% 4 4 4 5% 6% 24%	2730
	11th to 20th	Night	16% 12% 4 10% 6% 5% 4 4 6% 7% 26%	2663
	21st to end	Night	17% 14% 3 10% 7% 5% 6% 4 5% 6% 23%	2083
March	1st to 10th	Night	16% 10% 4 8% 6% 4 4 3 6% 7% 32%	5112
	11th to 20th	Night	11% 8% 3 8% 5% 5% 5% 3 5% 8% 39%	5089
	21st to end	Night	17% 10% 3 8% 5% 4 4 3 4 4 36%	5588
April	1st to 10th	Night	19% 10% 3 7% 5% 4 5% 4 5% 7% 32%	2225
	11th to 20th	Night	17% 7% 4 6% 5% 5% 4 3 6% 7% 35%	1925
	21st to end	Night	15% 7% 3 7% 5% 5% 6% 4 5% 7% 37%	1890
May	1st to 10th	Night	20% 9% 3 7% 4 4 4 4 5% 6% 33%	5257
	11th to 20th	Night	14% 9% 3 8% 5% 5% 5% 3 5% 7% 36%	5216
	21st to end	Night	18% 6% 2 5% 3 4 4 4 6% 7% 41%	5114
June	1st to 10th	Night	12% 5% 2 5% 4 4 4 4 7% 7% 45%	1680
	11th to 20th	Night	10% 5% 1 4 4 5% 5% 5% 8% 10% 43%	1531
	21st to end	Night	10% 5% 2 4 4 6% 5% 4 5% 8% 47%	1400
July	1st to 10th	Night	7% 5% 2 5% 5% 4 5% 4 7% 10% 47%	3199
	11th to 20th	Night	8% 6% 2 6% 3 4 5% 3 6% 9% 49%	4046
	21st to end	Night	7% 5% 2 6% 4 4 4 4 6% 8% 51%	4428
August	1st to 10th	Night	11% 5% 2 6% 4 4 5% 4 6% 9% 45%	2915
	11th to 20th	Night	9% 6% 2 6% 4 4 3 3 6% 7% 50%	2875
	21st to end	Night	8% 5% 2 5% 4 5% 4 4 6% 9% 49%	3277
September	1st to 10th	Night	9% 6% 3 6% 4 4 4 4 5% 7% 48%	2040
	11th to 20th	Night	9% 4 1 4 4 3 4 3 5% 7% 56%	2200
	21st to end	Night	15% 6% 2 6% 5% 5% 5% 4 6% 6% 41%	2200
October	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 7% 45%	2365
	11th to 20th	Night	17% 9% 2 8% 4 3 4 3 5% 5% 38%	2400
	21st to end	Night	21% 8% 3 8% 4 5% 4 3 5% 7% 32%	2653
November	1st to 10th	Night	14% 8% 3 5% 5% 3 5% 4 7% 7% 41%	2666
	11th to 20th	Night	16% 10% 3 7% 6% 5% 5% 4 6% 7% 31%	2900
	21st to end	Night	22% 12% 3 8% 6% 5% 4 5% 6% 6% 24%	2940
December	1st to 10th	Night	14% 15% 6% 12% 6% 6% 6% 4 6% 7% 18%	4720
	11th to 20th	Night	17% 20% 5% 10% 5% 4 4 4 5% 5% 22%	5348
	21st to end	Night	25% 18% 5% 10% 6% 5% 3 3 5% 5% 15%	7150

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% 10% 10% 10% 5%	5040
	11th to 20th	Day	77% 10% 6% 4 3	5280
	21st to end	Day	66% 9% 11% 8% 6% 1	5780
February	1st to 10th	Day	64% 7% 12% 12% 4 1	1890
	11th to 20th	Day	62% 7% 10% 14% 6%	1852
	21st to end	Day	60% 9% 12% 13% 5% 1	1720
March	1st to 10th	Day	58% 8% 14% 15% 5%	4950
	11th to 20th	Day	46% 8% 19% 18% 7% 2	5090
	21st to end	Day	52% 9% 12% 18% 9% 1	5586
April	1st to 10th	Day	51% 7% 12% 18% 10% 1	2394
	11th to 20th	Day	48% 8% 12% 18% 12% 1	2662
	21st to end	Day	47% 8% 13% 19% 12% 2	2730
May	1st to 10th	Day	47% 10% 14% 17% 8% 4	7651
	11th to 20th	Day	44% 11% 14% 20% 10% 1	7630
	21st to end	Day	38% 8% 11% 21% 19% 3	9061
June	1st to 10th	Day	37% 9% 14% 24% 14% 2	2940
	11th to 20th	Day	37% 10% 16% 21% 15% 2	2972
	21st to end	Day	33% 10% 16% 25% 15% 1	3000
July	1st to 10th	Day	32% 9% 15% 26% 16% 2	6701
	11th to 20th	Day	31% 8% 16% 28% 15% 1	5840
	21st to end	Day	30% 9% 16% 24% 20% 1	6240
August	1st to 10th	Day	37% 9% 17% 22% 13% 1	4221
	11th to 20th	Day	38% 11% 17% 25% 8% 1	4213
	21st to end	Day	34% 10% 16% 28% 12% 1	4587
September	1st to 10th	Day	34% 10% 17% 25% 13% 1	2356
	11th to 20th	Day	30% 8% 17% 29% 15%	2200
	21st to end	Day	44% 8% 15% 22% 11% 1	2200
October	1st to 10th	Day	34% 9% 17% 22% 18% 1	3306
	11th to 20th	Day	37% 8% 15% 24% 16%	3240
	21st to end	Day	46% 8% 17% 21% 7%	3511
November	1st to 10th	Day	46% 10% 14% 21% 7% 2	1852
	11th to 20th	Day	50% 10% 17% 14% 9% 1	1717
	21st to end	Day	64% 10% 13% 10% 3	1680
December	1st to 10th	Day	63% 11% 14% 9% 3	2680
	11th to 20th	Day	66% 9% 13% 8% 5%	3066
	21st to end	Day	74% 9% 9% 6% 2	4048
January	1st to 10th	Night	60% 13% 11% 12% 3	7837
	11th to 20th	Night	68% 10% 9% 8% 4	7680
	21st to end	Night	63% 8% 9% 11% 8%	8401
February	1st to 10th	Night	60% 8% 12% 14% 5%	2730
	11th to 20th	Night	56% 8% 15% 15% 6%	2665
	21st to end	Night	58% 8% 12% 15% 6% 1	2083
March	1st to 10th	Night	49% 6% 16% 18% 10% 1	5122
	11th to 20th	Night	39% 9% 18% 22% 11% 1	5090
	21st to end	Night	47% 7% 12% 16% 15% 2	5588
April	1st to 10th	Night	50% 7% 11% 17% 12% 2	2225
	11th to 20th	Night	46% 7% 11% 19% 15% 2	1925
	21st to end	Night	43% 8% 12% 20% 14% 3	1890
May	1st to 10th	Night	50% 7% 10% 13% 14% 6%	5264
	11th to 20th	Night	46% 8% 12% 21% 11% 2	5217
	21st to end	Night	40% 7% 11% 21% 19% 2	5115
June	1st to 10th	Night	35% 8% 12% 25% 16% 5%	1680
	11th to 20th	Night	33% 8% 16% 23% 17% 2	1531
	21st to end	Night	35% 7% 14% 24% 19% 1	1400
July	1st to 10th	Night	29% 9% 15% 25% 17% 5%	3164
	11th to 20th	Night	31% 7% 13% 28% 18% 2	3993
	21st to end	Night	30% 8% 14% 20% 24% 4	4297
August	1st to 10th	Night	34% 8% 15% 24% 17% 2	2904
	11th to 20th	Night	32% 8% 16% 30% 13% 1	2902
	21st to end	Night	30% 8% 13% 32% 16% 1	3277
September	1st to 10th	Night	35% 7% 14% 26% 16% 2	2040
	11th to 20th	Night	27% 7% 14% 32% 18% 1	2200
	21st to end	Night	42% 8% 12% 23% 13% 1	2200
October	1st to 10th	Night	28% 7% 11% 29% 24% 2	3872
	11th to 20th	Night	41% 6% 15% 22% 17%	3899
	21st to end	Night	38% 7% 17% 24% 12% 1	4277
November	1st to 10th	Night	41% 8% 15% 23% 12% 1	2666
	11th to 20th	Night	50% 11% 14% 17% 8% 1	2900
	21st to end	Night	58% 11% 15% 12% 3 1	2940
December	1st to 10th	Night	62% 11% 16% 8% 2	4720
	11th to 20th	Night	62% 10% 12% 10% 6%	5348
	21st to end	Night	69% 9% 10% 9% 3	7150

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	22% 21% 33% 17% 5% 2	289
	11th to 20th	Day	25% 16% 42% 11% 5% 2	330
	21st to end	Day	25% 18% 33% 20% 4 1	363
February	1st to 10th	Day	18% 20% 39% 19% 4	330
	11th to 20th	Day	24% 18% 37% 18% 3	330
	21st to end	Day	20% 25% 42% 12% 1	273
March	1st to 10th	Day	22% 14% 36% 22% 6%	493
	11th to 20th	Day	20% 16% 34% 24% 4 1	540
	21st to end	Day	25% 16% 33% 20% 6%	594
April	1st to 10th	Day	21% 14% 35% 22% 7% 1	540
	11th to 20th	Day	22% 15% 31% 19% 10% 3	532
	21st to end	Day	22% 10% 31% 27% 8% 2	540
May	1st to 10th	Day	20% 13% 30% 24% 11% 2	543
	11th to 20th	Day	17% 9% 26% 28% 17% 3	567
	21st to end	Day	14% 6% 26% 29% 20% 6%	617
June	1st to 10th	Day	11% 6% 31% 34% 15% 3	570
	11th to 20th	Day	10% 8% 24% 35% 18% 4	652
	21st to end	Day	12% 4 29% 35% 18% 3	730
July	1st to 10th	Day	8% 5% 21% 32% 26% 9%	702
	11th to 20th	Day	12% 5% 23% 29% 21% 9%	524
	21st to end	Day	9% 3 17% 39% 24% 8%	576
August	1st to 10th	Day	9% 3 17% 32% 27% 12%	526
	11th to 20th	Day	11% 4 16% 34% 23% 12%	519
	21st to end	Day	10% 3 18% 33% 27% 9%	583
September	1st to 10th	Day	12% 4 21% 28% 23% 12%	530
	11th to 20th	Day	6% 3 16% 26% 32% 16%	530
	21st to end	Day	17% 8% 24% 26% 17% 8%	530
October	1st to 10th	Day	17% 9% 26% 21% 21% 5%	530
	11th to 20th	Day	18% 14% 32% 26% 7% 2	530
	21st to end	Day	24% 15% 33% 21% 7%	568
November	1st to 10th	Day	18% 19% 32% 21% 8% 2	330
	11th to 20th	Day	25% 23% 27% 18% 6% 2	239
	21st to end	Day	26% 20% 36% 16% 2	220
December	1st to 10th	Day	28% 19% 30% 16% 5% 1	220
	11th to 20th	Day	30% 22% 30% 15% 3	220
	21st to end	Day	28% 19% 35% 14% 3	242
January	1st to 10th	Night	24% 17% 37% 16% 6% 1	840
	11th to 20th	Night	27% 19% 33% 18% 3	840
	21st to end	Night	20% 13% 39% 22% 6%	924
February	1st to 10th	Night	24% 13% 36% 24% 3	840
	11th to 20th	Night	22% 14% 34% 26% 4	823
	21st to end	Night	23% 14% 38% 23% 3	692
March	1st to 10th	Night	20% 10% 37% 26% 7%	840
	11th to 20th	Night	21% 11% 36% 25% 6% 1	840
	21st to end	Night	22% 11% 31% 27% 8% 1	924
April	1st to 10th	Night	22% 12% 32% 28% 5%	840
	11th to 20th	Night	20% 11% 31% 27% 10% 1	681
	21st to end	Night	20% 6% 31% 34% 9% 1	630
May	1st to 10th	Night	20% 7% 25% 32% 15% 1	630
	11th to 20th	Night	15% 5% 28% 38% 13% 2	616
	21st to end	Night	15% 3 22% 36% 22% 2	455
June	1st to 10th	Night	15% 3 23% 40% 18% 1	420
	11th to 20th	Night	11% 3 26% 41% 18%	410
	21st to end	Night	11% 5% 23% 42% 19% 1	400
July	1st to 10th	Night	6% 2 17% 42% 29% 3	390
	11th to 20th	Night	9% 4 17% 39% 28% 4	569
	21st to end	Night	10% 2 15% 45% 26% 2	657
August	1st to 10th	Night	8% 2 13% 39% 33% 4	597
	11th to 20th	Night	8% 3 14% 34% 36% 4	594
	21st to end	Night	9% 3 18% 40% 27% 3	688
September	1st to 10th	Night	11% 5% 19% 32% 28% 6%	800
	11th to 20th	Night	10% 4 13% 36% 33% 5%	800
	21st to end	Night	16% 6% 22% 33% 17% 6%	800
October	1st to 10th	Night	15% 7% 24% 32% 18% 4	800
	11th to 20th	Night	20% 13% 29% 27% 11% 2	800
	21st to end	Night	23% 11% 32% 28% 6%	880
November	1st to 10th	Night	17% 13% 28% 29% 12% 1	820
	11th to 20th	Night	21% 15% 35% 20% 7% 2	840
	21st to end	Night	27% 13% 33% 20% 6%	840
December	1st to 10th	Night	27% 18% 32% 18% 5%	840
	11th to 20th	Night	25% 19% 35% 18% 3	840
	21st to end	Night	28% 14% 33% 22% 2	924

Page generated at 2026-06-13 02:31:39. Version ac07

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