diff --git a/pkg/logger/file_logger.go b/pkg/logger/file_logger.go
index 8accb4c..1d951a1 100644
--- a/pkg/logger/file_logger.go
+++ b/pkg/logger/file_logger.go
@@ -4,13 +4,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
-	"sync"
 	"time"
 
-	"git.cryptic.systems/fh-trier/go-flucky/pkg/internal/errutils"
-
 	"git.cryptic.systems/fh-trier/go-flucky/pkg/types"
 )
 
@@ -101,82 +97,78 @@ func (fl *FileLogger) GetTemperatures(from *time.Time, till *time.Time, sensorID
 	return cachedTemperatures, nil
 }
 
+// LogHumidities write humidities to all configured humidity logfiles
 func (fl *FileLogger) LogHumidities(humidities []*types.Humidity) error {
-	countLogfiles := len(fl.LogFiles[LogHumidity])
-	wg := sync.WaitGroup{}
-	wg.Add(countLogfiles)
-
-	errChan := make(chan error)
-
 	for _, logfile := range fl.LogFiles[LogHumidity] {
-		go func(humidities []*types.Humidity, logfile string) {
-			defer wg.Done()
-
-			// read existing humidities as bytes
-			bytes, err := ioutil.ReadFile(logfile)
+		logHumidities := []*types.Humidity{}
+		// if logfile already exists, read humidities from logfile
+		if _, err := os.Stat(logfile); err == nil {
+			f, err := os.Open(logfile)
 			if err != nil {
-				errChan <- err
-				return
+				return fmt.Errorf("Can not open file %v: %v", logfile, err)
 			}
 
-			// convert bytes into humidities
-			logHumidities := []*types.Humidity{}
-			err = json.Unmarshal(bytes, &logHumidities)
+			decoder := json.NewDecoder(f)
+			err = decoder.Decode(&logHumidities)
 			if err != nil {
-				errChan <- err
-				return
+				return fmt.Errorf("Can not decode humidities from reader")
 			}
 
-			// append new humidities with exsisting humidities from logfile
-			logHumidities = append(logHumidities, humidities...)
+			f.Close()
+		}
 
-			// convert humidities into json file
-			bytes, err = json.MarshalIndent(logHumidities, "", " ")
-			err = json.Unmarshal(bytes, &logHumidities)
-			if err != nil {
-				errChan <- err
-				return
-			}
+		// append new humidities with existing humidities from logfile
+		logHumidities = append(logHumidities, humidities...)
 
-			ioutil.WriteFile(logfile, bytes, os.ModePerm)
-
-		}(humidities, logfile)
-	}
-
-	wg.Wait()
-
-	errList := errutils.CollectErrors(errChan)
-	err := errutils.FormatErrors(errList)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
-func (fl *FileLogger) LogTemperatures(temperatures []*types.Temperature) error {
-	for _, logfile := range fl.LogFiles[LogTemperature] {
-
-		logTemperatures := []*types.Temperature{}
-
-		// open logfile
-		f, err := os.OpenFile(logfile, os.O_RDWR, os.ModePerm)
+		// overwrite lofgile with new entries
+		f, err := os.Create(logfile)
 		if err != nil {
 			return fmt.Errorf("Can not open file %v: %v", logfile, err)
 		}
 		defer f.Close()
 
+		// encode humidities
+		encoder := json.NewEncoder(f)
+		encoder.SetIndent("", " ")
+		err = encoder.Encode(logHumidities)
+		if err != nil {
+			return fmt.Errorf("Can not encode humidities for the writer")
+		}
+	}
+
+	return nil
+}
+
+// LogTemperatures write temperatures to all configured temperature logfiles
+func (fl *FileLogger) LogTemperatures(temperatures []*types.Temperature) error {
+	for _, logfile := range fl.LogFiles[LogTemperature] {
+		logTemperatures := []*types.Temperature{}
 		// if logfile already exists, read temperatures from logfile
-		if _, err := os.Stat(logfile); os.IsExist(err) {
+		if _, err := os.Stat(logfile); err == nil {
+			f, err := os.Open(logfile)
+			if err != nil {
+				return fmt.Errorf("Can not open file %v: %v", logfile, err)
+			}
+
 			decoder := json.NewDecoder(f)
 			err = decoder.Decode(&logTemperatures)
 			if err != nil {
 				return fmt.Errorf("Can not decode temperatures from reader")
 			}
+
+			f.Close()
 		}
 
-		// append new temperatures with exsisting humidities from logfile
+		// append new temperatures with existing temperatures from logfile
 		logTemperatures = append(logTemperatures, temperatures...)
 
+		// overwrite lofgile with new entries
+		f, err := os.Create(logfile)
+		if err != nil {
+			return fmt.Errorf("Can not open file %v: %v", logfile, err)
+		}
+		defer f.Close()
+
 		// encode temperatures
 		encoder := json.NewEncoder(f)
 		encoder.SetIndent("", " ")
diff --git a/pkg/logger/logger.go b/pkg/logger/logger.go
index 19d5bc3..46e12ed 100644
--- a/pkg/logger/logger.go
+++ b/pkg/logger/logger.go
@@ -8,7 +8,7 @@ import (
 
 type Logger interface {
 	GetHumidities(fromDate *time.Time, tillDate *time.Time, sensorNameOrUUID *[]string) ([]*types.Humidity, error)
-	GetTemperatures(fromDate *time.Time, tillDate *time.Time, sensorNameOrUUID *[]string) ([]*types.Temperature, error)
+	GetTemperatures(from *time.Time, till *time.Time, sensorIDs []string) ([]*types.Temperature, error)
 	LogHumidities(humidities []*types.Humidity) error
 	LogTemperatures(temperatures []*types.Temperature) error
 }